Picture of DIY Light Transmitting Concrete (+ HD Video)
Make sure to check out my blog!

I'm going to show you (as best as I can) how to make light transmitting concrete. Google it, and you will be amazed at how beautiful it is! I was desperate to get my hands on some...but considering the cost, I decided to make some with stuff I already had around.

This material has the strange effect of looking shiny or sparkly...but it's dull concrete at the same time! It's very entertaining to show off or play around with.

If this material interests you, check this article out:

Here is the HD video:

Here is the normal video:

Step 1: Making The Mount

Picture of Making The Mount
 You need to roll some polymer craft clay into a flat circle. Make it as level as possible.

wow, that's really terrific!

Travpena1 year ago
im going to take this technique and make constellations with different shapes and the sort, thanks for the idea
Ogredude3 years ago
This is an awesome instructable!  As soon as I saw it, I knew I needed to do a project with this technique.  But what to make? One of my friends owns a concrete supply company, so I put his logo in the concrete. He was very happy to receive it as a Christmas present!

I ended up having to make this thing twice. The first time, I really messed up the water to concrete ratio on the mix, and when I tried to demold it, it was very crumbly and pretty much fell apart.


I took photos of the construction of the first one, but didn't photograph the second one until it was complete. I learned quite a few little techniques on the first try that made the second attempt go much easier, so I'll describe those techniques as I go.

I started with the clay base. Then I printed his logo in black on my HP inkjet printer, cut it out, pressed it onto the clay, then wet the back of the paper and dabbed it a bit with my finger. HP inks are water-soluble, so when you peel the paper away, it's transferred enough ink to see what you're doing onto the clay.


The second time round, I decided that was still too hard to see, so I filled the design in with Sharpie. This helped a bunch.

I started putting fibers in one by one with plastic tweezers, but the fibers are so low-contrast that I had a very hard time seeing where they were going and where they needed to be.


So I used a highlighter to color about the last quarter inch of the fibers, and worked under a blacklight, and I could see what I was doing just fine. The inked part of the fibers ends up in the clay, and it doesn't bother the finished piece.

I also discovered that an incense holder makes the perfect staging area for fibers, the ash trough makes it very easy to pick them up individually with the tweezers.


After it was cast (and I fixed a crack with epoxy), I polished it up as best I could on a disc sander (killing 2 discs in the process), and covered it with several coats of triple-thick glaze.


On one side is random dots of light...


On the other, a logo!

nepheron (author)  Ogredude3 years ago
Hey that turned out great! What kind of fibers did you use?

Oftentimes, crumbling happens because of too much water. In order to get regular concrete thin enough to fill the spaces around the fibers, it's too wet and cures strangely. Rocktite is really magical stuff, you can't add too much water. It pretty much cures no matter what.

A secret I learned from casting lots of stepping stones is that once you open a bag of concrete, you have to either use it within 24hrs, or put it in an airtight garbage bag and seal it really good. Old, opened concrete will pretty much crumble no matter what you do with it (absorbing water in the air reacts the lime in the micture)

Rocktite seams to work fine even if its left exposed for a very long time.
Oh man, I forgot this comment was even out here!

The fibers I used were from an LED fiber optic lamp I found at the dollar store. I snipped them to length with scissors.

I presented this piece to the owner of the concrete business, he really enjoyed it.

He gave me some tips on working with concrete. Firstly, concrete will always shrink a bit. If you don't want your piece to shrink, use non-shrinking grout mix instead. (he gave me an 80lb sack, yay!) He said it probably crumbled because I put too much water in. The grout apparently doesn't have that problem, you can mix it thinner if you need.
shaoran182 years ago
Thank you for posting this
Probedude3 years ago
The most beautiful fiber optic in concrete art I've seen is by the artist Clyde Lynds.
First saw an example of his work back in '88. Looks like he's gotten more sophisticated.
just to add a similar idea I recently heard.
My Cousin is in Peru helping villagers to add sky lights to their huts. They use a clear plastic pop bottle filled with water (clorinated to keep out green stuff)
It is embedded in the ceiling and sticks out of the roof. It channels sunlight into the hut and apparently lights up as well as a 60 watt light bulb. As long as the sun is shining!
here's the link to the project. i made one for our shed here in thailand, it's so simple but works wonderfully! http://isanglitrongliwanag.org/
erronius3 years ago
My friend Karl (KRЯRL to the rest of the world) and I have started putzing around with fiber optics in a fine concrete or mortar. KRЯRL scanned a small relief his friend made from one of his unique figure drawings and had the scan printed into a large styrofoam (polystyrene for the Brits?) negative. The styrofoam served as both a mold for the concrete and a soft substrate to poke the optical fibers into.

you can read about the process on Karl's blog at:

Nice project!
Rienei3 years ago
Hi, may i know if the following 2 works :
1) Sticking the fibres into the concrete AFTER pouring the concrete into a mould,
2) having less space in between the fibres to allow more light to pass through

Thank you in advance :D
Oscelot Rienei3 years ago
I doubt sticking the fiber into the concrete afterwards would work too well, you'd get concrete on the ends and end up with it looking fairly dull, in my opinion. I don't see why you couldn't stick as many fibers in as you want to. Just my opinion.
chibisuke114 years ago
can i use white cement? please reply ASAP :)
You may want to try to find a book called Sculpting With Cement by Lynn Olson. He uses white cement extensively on the outside of his concrete sculptures
DeeRilee3 years ago
I think I might try making the "bowl" of a birdbath this way! It might make for some interesting sparkles of light on the ground surrounding it! (hopefully!)
pbecker834 years ago
Pretty neat. I'd like to see some night time video.
LMas4 years ago
Really nice project!!!!
Oh my... "Light" project are always interesting.
erronius4 years ago
LOL: agggh! another excuse to make a variant of the infamous Austin Powers Tent Scene!

Here are a couple other things i was thinking abewt:

1) if you want uniform light transmission, maybe one could use a mesh or some such thing to distribute the fibers evenly over the surface.

2) Well, what about non-uniform light transmission????!!! Sounds like something with real potential to me. What if you varied the density? You could create areas of gradient,highlight or shadow or an entirely new design or swirly pattern within your piece, which could really add an interesting dimension to a sculptural piece that was a low- or medium-relief.
you could also leave the extra length on the fibers and use something (like paper or thin cardboard) to block some of the fibers from others and using led's light different sections with different colors. this could make a great yin-yang effect with the circle that was made in this ible.
wobbler4 years ago
Instead of making the clay into a flat circle, you could first make it into a long square profile strip. Then place your fibre optics all along the length of one side on the top surface. You wouldn't need to push them in, simply lay them on the top, so it should be quicker. You could then lay another long thin bit of clay on top to hold them if needed. This could then be rolled up to create a spiral. Alternatively, you could lay this out in a shape and then fill in the gaps with either wax or more clay before pouring the concrete.
phapboy4 years ago
SO COOL! Now I wanna see someone mash this project and this project!
MissCindel4 years ago
I like the image as it is held up to the light ... and started thinking that the fiber optic strands could be assembled in the clay in a pattern too :*)
erronius4 years ago
So you used an amended plaster, like hydrocal or ultracal? That's pretty interesting. Looks like you could do any kind of piece that has low relief.

You know, if you want to color the material, you don't necessarily have to use paint. You could conceivably use a colorant, like iron oxide (or one of those marking powders they use for carpenter's chalk lines, some of which are iron oxide) or a mason stain (sold at ceramics places) and mix it into your goop. If you are using cement, you can make it brighter and less gray by using white Portland cement instead of the ordinary dingy gray variety.
Broom5 years ago
I'm suddenly thinking of a concrete countertop, lit from below! OK, it won't be bright enough to see by, but super-cool accent lighting. Or - the most awesome bar counter ever!
Did any of you ever do the glass in counter-top?
I'm searching for a way to clean up the crushed glass from the recycling center to use. It's got too many label bits stuck to the glass.
Put the glass in a roasting pan, and cook in the oven at the highest temperature (clean mode, if you have it) for an hour or two. The labels will turn to ash.
Valster Broom5 years ago
My tropical theme bar is finished except for the counters...  Remote light wheel with color change or twinklie effect?  Waves, palm trees, tiki head patterns?  The possibilities are endless!
making the top of the counter from concrete with fiber optics incorporated like in this tutorial but insead of cutting the fiber short connect them as bunches to a light source, like a light engine with a controller and you can make your bar rock!!
nepheron (author)  Valster5 years ago
 This may be a bit out of your price range, but putting an LCD screen underneath this stuff looks amazing! The colors are pretty crisp, but 'pixelated' so a large design would be necessary.
Moralito Broom5 years ago
Bar counter is the way to go....Simply awesome...
nepheron (author)  Broom5 years ago
I think there would be enough light to see by! There is very little loss in the fiber optics.
Broom nepheron5 years ago
Not the point. The light is coming from below, making everything on the counter backlit, and therefore (I bet) darker by contrast than if the counter weren't lit.
Valster Broom5 years ago
Broom, I just realized how awesome drink glasses will look when lit from underneath.  I have to do this!
If you placed it on the vertical edges then you would be able to see the edge in the dark. Keep you from bumping into it at night!
itwasalan Broom5 years ago
It would be really cool if the fibre optics could cause glass aggregate in the concrete to glint or twinkle too.  I was going to do concrete counter tops in my kitchen anyway.  Time to do some proof of concept experiments.
what about a layer of fine crushed glass on the side facing up?

I made some fine crushed glass with a capped steel pole and a baseball bat. Just pound away until its like a dust.
hishealer Broom5 years ago
 Not only that, but you could spell out Welcome or make pictures with the "pixels"...
Combining that with mrfusi0n's idea above, that would be really cool.

dfc849 Broom5 years ago
afroray4 years ago
thank you so much now i have a experiment to try out :) also a quick question do you think this would work if i use plaster of paris?
nepheron (author)  afroray4 years ago
Thanks! Plaster will work fine.
sith_gundam4 years ago
This is not real translucent concrete, it's just a mix of ceramic glue and optic fiber.
The true litracon (or a near version) uses a mix of fluorite, cement and fiber glass.
thepelton4 years ago
Neat! It's only fifty years too late for the Fallout Shelter building boom. Happily, they never had to be used for their original use.
happyadrian5 years ago
 Do any of you know how I could implement beach sand into the concrete? Do I just mix it in? Sorry, I'm inexperienced with these materials. I want to make the object look more like a sandy rock. Would I use a substitute for the concrete?
nepheron (author)  happyadrian5 years ago
 The material I used is technically called cement. When you mix cement with something like pebbles, SAND, or rocks you get 'concrete'. Try mixing a little of your cement with sand, and see what it looks like before you make a large piece.
Cement - or Portland cement reacts with water to harden. The cement and water is called the paste. Sand and stone is added to concrete mainly to make it less expensive. It takes up space that expensive paste would have to fill. Also, paste can shrink, so adding stone and sand makes concrete shrink less.
Beach sand contains salt - calcium chloride. Salt causes steel corrosion so not recommended anywhere near steel. To remove salt, you would need to wash it extremely well.
Beach sand is not a good idea. The salt will cause problems. I have read up a LOT on these ideas and all people say no beach sand.
rogofor5 years ago
Keep water content low for stronger concrete. If using glass fiber, remember that it should be alkali-resistant glass. Panthon in Rome used pumice aggregate. (Foamy volcanic rock).
gemtree5 years ago
Thank you for posting this. Me a happy camper. I may try some fiberglass scrim for holding the fibers.
gemtree5 years ago
Arggghhhh. I have been wanting fiber optic counters for years. Ever since I got a magazine by accident sent to the people that USED to own the house. *whimper*
Fizzxwizz5 years ago
Is there a place that I can buy these plastic fiber optic strands? I saw fishing wire mentioned, will that work as well? I was wondering this because I didn't want to have to buy a cheap toy just so I could cut it up. One last question, would permastone work as a substitute the concrete? I was just wondering as I don't know much about this permastone material.
nepheron (author)  Fizzxwizz5 years ago
I'm sure fishing line would work great. Make sure you get the thickest variety, probably 20 - 30 lb test. Also make sure it's clear, as some line comes in colors. If permastone cures hard like concrete (and not rubbery or something), it will work fine. Good luck!!
Transquesta5 years ago
Agreed, nice work, but there's gotta be a way to 'mass produce' the same or similar effect.  Maybe using glass beads?  The reason I'm interested relates to oldhamedia's idea below: an under-lighted walkway using, say, rope lights, but which covers a wide/wider area.

oldhamedia5 years ago
 Ooh! I'm going to use some of my solar cell LED path lights and cast stones to line the sidewalk down my stairs with this instructible!

Nice work!
shaawn5 years ago
Isn't it porous? Wouldn't water seep through, or air? What about plastic fibres? Glass fibres? Why fibre opticals?
nepheron (author)  shaawn5 years ago
All concrete is water permeable. Concrete, if mixed properly, is not porous to air. I used plastic fiber optics in this ible because glass fiber optics are dangerous to handle. Glass fiber optics are clearer than glass fibers, but over a thickness of a couple inches there is little difference in light transmitting abilities.
shaawn nepheron5 years ago
Thanks for the reply. I replied a little hastily to the forum, I then read a little further and saw the issues I raised were sorta' already covered. I had never heard of plastic fibre-optics! Any-how, it looked great, I thought of bottle walls and roofs, combining fero-cement with transparent elements...glass rod or plastic, lensed pipe..  Fero- cement experiments are here in the planning with sawdust as the main ingredient to get as light and thermally insulating a wall/panel as possible. Seems such a practical mix, I don't know why it's not more popular?! A sawdust brick range has been patented in Australia. Still fire-proof after high sawdust ratios! I'm trying to find a cheap, bulky, light, fireproof, insulating material + waterproof would be perfect. After much research (theoretical, mainly internet browsing) I think a mix of 1-cement, 1 - 2 sand, 5-8 sawdust and 1 slaked lime might be it. ( I now have the sawdust, different wire and steel meshes and frames for experimental panels, just need a little cement and slaked lime. Gonna happen in the next week).  Maybe you have some knowledge of this-all or some links?  Thanks again  - Shawn
skinny*k shaawn5 years ago
The oculus of the Pantheon in Rome is only somethong like 30% concrete—the rest being lighter fill material—and it has stood the test of time. The link might give you some other ideas. Straw can also be used for filler material and, if not overdone, will not make a structure lighter, but stronger, owing to the strengthening wall surfaces inside the concrete. The fibers would have to be pushed thru, though, not poured around.

Also, we used to use monofiliment fish-line for fiberoptic lamps and art; its way way way cheaper by the foot than plastic fiberoptic cable. The results look the same to the eye, it just isn't suitable for data transmission.
nepheron (author)  skinny*k5 years ago
 Fishing line? I'd never thought of that!
Monofilament would make even very large projects economical.

BTW, in my first post I meant to say, "... will not ONLY make a structure lighter..."

It will make it lighter, of course.

Your ible has set my mind in motion; cool. I'm thinking of replacing half of a dying  sliding patio door with a panel of this translucent concrete. Thanks.
 I think fishing line is as versatile as duct tape!  I've even sewn with the finer stuff.
 You have to be careful with the sewing; on flexible items, like blankets, it will cut thru the fabric. It is pretty useful stuff, tho.
 Very good to know, ty ^.^
shaawn skinny*k5 years ago
I recently read somewhere how to make nylon strands with two chemicals in a glass ( I'll find it and post the link) You'd probably be able to control the thickness of the strands and maybe get something a little thicker than the usual fishing gauges. Apparently it can be alittle brittle, but the transparency and not the strength the criteria here?

 Sorry; forgot to post the link:
shaawn shaawn5 years ago
I got some cement and lime and did a test today, I think in my eagerness to use as much sawdust as possible I've used too much! I've done:  1part cement - 1sand -1lime- 7sawdusts. It won't have any kind of strength. It seems like a cow-patty 9 which I think might be stronger.
nepheron (author)  shaawn5 years ago
 Believe it or not, plaster of paris is a remarkably fireproof material. It has almost no expansion and is porous enough to let water vapor escape (and not explode or fracture). You have to experiment to believe it!

In Africa, carbon ( like black charcoal) is added to river clay to make it able to withstand repeated firings. This 'fire clay' is used to make kilns and glass slumping molds.
 Do you have links to those ferrocement plans? Pictures?
mrfusi0n5 years ago
First of all, this looks so cool!

I had a couple ideas (I'll post them separately). First, to more quickly place the fibers in the clay, I was thinking that, after you cut them to length, you could line them all up (perhaps in a shallow tray of some sort) and then use a thin but long strip of tape (double sided?) to pickup the fibers. I'm picturing the tape running perpendicular to the direction of the fibers. This should create something like a "rope" of fibers that could be snaked along the clay (sticking the fibers on one side of the tape into the clay). The tape itself should end up completely surrounded by the cement. The end result might look a little different since the fibers would be sort of lined up instead of totally spread out but I think it might look ok. Ideally there would be some space between the fibers stuck to the tape and not totally side-by-side. This is just an untested idea...
ajxl mrfusi0n5 years ago
That would make writing or picturing a lot easier.  Just guide the tape in the directions you want it to go.  Thanks for a great idea!
nepheron (author)  mrfusi0n5 years ago
 Untested or not, that sound like a pretty good idea!
trainables5 years ago
Don't they make special tools for mounting hair in prosthetic appliances?

Or maybe you could build a rig out of plastic; make a top and bottom piece with evenly spaced holes in them and thread the fiber optic through both, and then mount the rig inside a mold and pour the concrete.  Maybe stretch clingfilm over the bottom piece before threading through the fiber.  Don't know if it would work, but it could make larger scale production easier.
the tool I've used for punching hair most into prosthetics is essentially a medium sized sewing needle, with the point glued into a dowel or crimped into a handle, with the thread loop cut to become a "pusher"
with a single longer tine and a small bifurcation to push the hair into place. we were punching hair into silicone or foam latex, though.
maybe if you used painter's canvas and either laid a dot pattern out or just punched the little fellas through how ever maybe a little UMR or spray release so the canvas doesn't bond to the cement.

awesome Ible, nepheron!

how about this.

A layer of wax
A piece of screen raised quarter of an inch above that
Fill every hole with 1 strand
pour wax until it covers the screen
and finally cement
sounds like it would work to me!
great idea, drakesword!
y'know it occurred to me.... those little polywhisker light guys, if you attached them to LEDs (or didn't trim them off the light source) and made a quicky mold of an inflatable ball, then cast them in as a quarter or half dome ( 1 1/2" walled hollow)
you'd have a very pleasing nightlght or sconce, i could even see using the pumpkin-stencil idea in conjunction with your fiber segregation screen idea to create awesome picture lights...
seems like it would make it easy to do ben day dots & halftone patterns too!

I'm going to try it.

Some pictures so far

First picture is a typical flagstone. Some are perfect squares. I don't like that!
Imperfection is cooler

Second picture is the box.

There is a single piece in it which can be placed and moved depending on what shape I want.

I want each stepping stone to look unique so i will have to make the dividers movable

The third is of  a light on the optic fibers held together with my hand (the uv light shows up so bright on camera!)
i have all of the materials to make the wooden jig. My dimensions shall be about 2ft x 1ft x 3in. I will post results when I have them.
drakesword5 years ago
I just had one of those awesome idea moments

First off i did some modifications

For a rock like effect I made a clay layer on top of the wax layer to give it some rough pits and groves.

I made the fiber optics long enough to be bound and moved off to the side.

here is where my idea starts

Just messing around I put a blue and a uv led behind my rock. 
to get some cool effects so I could make a "zen garden" with mood lighting!
Also as far as a pathway jig I think
--> a piece of 3/4 in plywood with fiber optic pilot homes
--> spreayed with some sort of urithane
----->procede to place optic strands in holes
----->Thin layer of wax (hold strands, prevent sticking, easy to break)
----->Then your cement (i used mason cement for my stone)

Then bind all of the strands in one area
Followed by solar garden light
MoGryph5 years ago
Looking at the almost-final product you have here, it looks like you might be able to get a second "brick" in a shortened amount of time.
Perhaps, while it's still in the mold but cured a number of hours, you can spray something such as spray-on silicone or even PAM, onto the surface that still has fibers sticking up out of it, and lay down a second layer of cement, let that cure, and then separate both.
Perhaps twisting the 2 pieces at the separation point, or running a long blade (such as a hacksaw blade) between the two would separate it without breaking the strands - not sure, maybe the lubricant would cause the fibers to slip right out of the concrete, but it might be worth testing out. If the fibers get a bit damaged from whichever method you separated them with, you're going to sand it down anyhow, so you'll probably end up sanding past the frayed parts.

Thanks for the fantastic Instructable!
what about a second layer of clay?

Or build the mold so it forms on its side with the clay going up the middle and both ends?

like this

Mold Clay Cement Clay Cement Clay Mold
Just hit me. use longer strands mount all of them in wax like it was previously said. then layer concrete and melted wax and shazam layered.
weibbed5 years ago
Thanks so much for this instructable.  Way cool.
Disneyworld has fiberoptics wired through the concrete sidewalks in the center of Epcot.  I imagine you could use pizzaboxes as molds for patio blocks, and use a connected fiber optic system to create the fibers, instead of cutting them off a toy?  Wouldn't that make a cool patio?
The next issue you would have to resolve would be the placement and sealing of the lighting element. If its solid state you may want to use silicone sealant and just fill it up without blocking the light. I guess you would have to add some sort of cavity under the slab to keep it in place
MoGryph5 years ago
I haven't used the stuff, but I was thinking - there are pigments that can be mixed into concrete to give it color- perhaps those same pigments can be used with the Rockite cement.
nepheron (author)  MoGryph5 years ago
 Look for 'Mosaic grout pigments'. They are fairly cheap and easy to use :)
jstkatz5 years ago
 Hey, just a thought, but have you tried burning off the fibers that stick out of the concrete afterwords, that is how it is done when they use polymer fibers to reinforce cement, the flame may even polish the ends of the strand and give you better light transmissions, worth a try probably
kaptaink_cg5 years ago
Awesome Instructable!! Such a great yet simple idea!

There are lots of great ideas in the comments as well. 

Has anyone tried arranging the fiber optics into a design? or picture?  (think of the old dot matrix black/white photos)
rkhpa5 years ago
This is a great thread and 'ible. Thanks.
This company is doing some of this type of stuff, though not quite as cool, in concrete and acrylic.
nepheron (author)  rkhpa5 years ago
 Sensatile looks pretty cool! I should visit them, I live nearby :)
rkhpa nepheron5 years ago
Yeah, I'm in ann arbor.  I keep meaning to get over there and check them out. I'm hoping they have some seconds to play with.
Sharkzz5 years ago
What brilliant ideas !!!
in regards to lighting for the bricks, a battery case available at most electric hobby/toy shops with a switch and light globe/s of your choice can be placed inside the brick when making the brick.
this has opened a can of  worms i am sure. can't wait to experiment as I am writing this. thanks all !!
jongscx5 years ago
I'm always looking for mass-reproducibility when I see projects on this site... just who I am I guess.

Anyway, could you:
1)use a long PVC pipe, slit in half and re bound into a tube, with mold release applied, as a form,
2) string long strands of fiber optics running along the length
3)fill with concrete (how to keep the fibers interspersed in the middle, I don't know) and let set
4) cut the concrete cylinder with a rock saw into disks and polish

I dunno, any thoughts?
Broom5 years ago
Is there any way to favorite this 100x more? Between the original 'ible, and the great comments growing out of it... Damn!
great instructable!
yo said somewhere in the comments that you had experimented with strips of water bottles in place of the fibre optics. any picture of these? would be interesting to see
nepheron (author)  drummonkey925 years ago
 Alas, I have not yet made a light transmitting brick with water bottles yet. I have done some experiments with water bottles since I posted. Cutting a water bottle into inch-long strips make pretty good fiber optics.

I wonder!!!! Is it possible to do a wall like this, not a big one, Down to B&Q again i suppose.
nepheron (author)  bobbelsekwol5 years ago

light-transmitting concrete.jpg
I have not tried this myself, but to make multiple tiles:
Do as instructed above, but use longer fibers and a deeper dam wall.
Then after it cures pour a thin layer of plaster of paris or some other water soluble solid. Let that cure, then pour another layer of cement. Alternate water soluble with cement until you fill the container. Wash out the plaster, break the glass, polish as already instructed. 
If only there were a faster way to mount the fibers...
Zing! Brilliant.

And the faster way to mount the fibers is... in wax.

Bundle the fibers at one end. Cool melted wax until it is nearly ready to solidify. Dangle the fibers into the wax, and spritz with spray bottle of water to congeal the surface quickly. It might take more than one bundle to cover the entire tile area.

Then proceed with your tile-layering idea!
netgrazer Broom5 years ago
Yessss, that's the kind of automation I needed but couldn't come up with. Thank you both, and thanks Nepheron of course!

For larger surfaces, you could make a board as large as the surface you want to make, and fix several bundles in it, with sticking tape or something.

Lower the board to dip the fibres in the wax, and pour the concrete in evenly spaced holes you made in the board in advance.

After the concrete has hardened, you could use a hot wire (like you use for styrofoam cutting) to cut all the fibres at once (if they're made of plastic).

You can also leave the bundles intact to connect a light source to it like Drakesword suggested below.

Remove wax, use an orbital sander or something, and you're finished.

Too bad that method wouldn't quite work on heavy walls... or maybe it would?
Either you need a machine to put the wall upright, or you could do it block by block, making sure the fibres are nicely distributed along the edges to make it look continuous. The possibilities!
Broom netgrazer5 years ago
God, together our hive mind is almost dangerous!
netgrazer Broom5 years ago
Resistance is futile! :)
mrfusi0n5 years ago
My second idea was that if you were scaling this up to make a brick-sized block, there's no reason the fiber optics would need to go straight through the cement. You could have them all bundled together on one side and spread out on the other. Once it's all encased in cement, place a light behind the fiber bundle and it should light up the entire other side!
roadieflip5 years ago
They have optical cables in the pound shop for - yes, you got it - a pound.

Looks like I'm gonna have to give this a go...
aleji77a5 years ago
just beautiful!
hollybd5 years ago
awesome instructable! im definitely going to do this
bowmaster5 years ago
This is awesome. I am going to do this, but with a ton more fibers.
zack2475 years ago
imagine this, but with a sphere! if you put a white led into the mold, then you can make it light up in the dark too!
Covo5 years ago
 The Video does not do it justice, I had no Idea it was so thick!!!  I'm with you Broom...imagine a bar with a concrete top made of this stuff.     Ideas-a-flowin'!!!!
dfc849 Covo5 years ago
There is an purely genius i'ble where a person molds a computer desk with fiber optics. 
mcbeth535 years ago
I'm thinking that you might be able to use embroiderer's plastic canvas to help disburse the rods finely and evenly.  Plastic canvas comes in various grid sizes, from four spaces per inch through 18 or so.  You could lay a piece of the grid on top of the form and push the rods through the openings.  I don't have any of those rods handy or I'd try them out for you.  Maybe I'll give this a try and report back in the future.
whiteoakart5 years ago
Nice job.  I have thought about doing this over the last couple of years but simply do not have the patience.

I saw this in an architectural magazine a few years back.  As far as I know, that designer was the originator of the idea.  He had an entire wall made of this stuff.  It was absolutely stunning.

If I can dig up a pic of it, I'll post it.  You could see the entire silhouette of a person walking by on the opposite side.
Actually, your link has some pretty nice photos on it.  I should have checked there first.
bxridley5 years ago
 Pretty damn genius.  I have a bundle of .24" clear acrylic rod that could be used for this, but I like the starlight bits of light you have coming out of yours.  Well and clearly done and inspiring.

nepheron (author)  bxridley5 years ago
 It will look good with .24" rods if you scale it up. Make cinderblock sized cubes of this stuff :)
RE: scale
 Yeah, I was thinking about 12" diameter, 2-3" height, ovals or circles, to use as stepping stones or exterior wall decoration, and power it by solar, 
BeanGolem5 years ago
 Well done. again.

Seems like it could easily be expanded to some killer LED backlit pathway stone pavers.
Or bunch the glass into a small area, lit with LED via USB, have it a very colorful lit paper weight, or a lit concrete coaster.
nepheron (author)  BeanGolem5 years ago
Hmm...that sounds like an interesting idea...
With a bit of patience, one could make a few very large pieces..
 And combined with other Instructables:

omg, I had the same idea!
 Or make a faceplate cover for an LED analog clock for a more artsy feel:

servant745 years ago
I tried to make a concrete table top for my daughter by using a different technique.   I wish I had seen this first!  It came out OK, but the fiber didn't workout.
jeff-o5 years ago
Super cool!  Got any tips on making a larger diameter or thicker slab in an efficient manner?
nepheron (author)  jeff-o5 years ago
 A 'mesh' made of fiberoptics can be layered into multiple pours of concrete. This way, it 'transmits' light through 4 sides instead of just 2. Does that make sense? it's hard to explain... :D
jeff-o nepheron5 years ago
Yeah, I can see what you mean.  But, I'd only need light transmitted through two sides.  I'm considering making some garden stepping stones.  It's either this method, or embedding glow-in-the-dark pellets.
elgorgo5 years ago
i'm thinking of the back lighting,
suggestions for garden ambience anyone?
Nice. I can also see this working with larger-diameter glass or acrylic rods. I think I'll go build a bomb shelter with a skylight... ;-)
nepheron (author)  RavingMadStudios5 years ago
 Use acrylic. Glass is a huge pain to work with...
I've done some research into using plastic bottles as the fiber optics...beleive it or not, it actually works...
Cutting a plastic bottle into strips no longer than 2 inches work pretty good as fiberoptics.
drakesword5 years ago
place the ends of the fibers the same way but have them much longer.

pour the concrete as usual.

bind the loose ends of the optics together and hotglue onto a solar pathway light's led and tada all done. Solar concrete pathway
_mattb5 years ago
totally cool.  out of curiosity, did this take long? 

Love the electric mini kolimba and hickory bow on your blog too.
nepheron (author)  _mattb5 years ago

It took me maybie an hour to put it together. Maybie overnight to let the concrete cure.
 or a 3-color led coaster?

you could strip the leds from the fiber optic toy you used