Introduction: LED Resin Cube

Picture of LED Resin Cube
Hello Again,
I've been wanting to use clear casting resin ever since I saw it used in this brilliant Instructable by Koogar.  Before I took on something as big as Koogar’s project, I wanted to start small so I came-up with “LED Resin Cubes”.

The idea behind the LED Resin Cube was inspired by a mercury switch that I found at my local electronic store.  I love the simplicity and look of this switch and wanted to incorporate it a project so you could see the switch in motion.  As the switch is made of glass and fragile, it’s pretty important to encase it in something strong – hence the clear resin.   

Check out the video below to see the LED Resin Cube in action.

This is a really easy project to do and the end result looks pretty cool.

Step 1: Things to Gather

Picture of Things to Gather


1. LED lights.
I used these lights from eBay but it is up to you what type of LED light you want encased.  The LED's I used change colour everytime you push the swich, and for the last change the lights flash!

2. Batteries. 
I used these batteries from eBay.   They are small button batteries that can re-charge and throw out 3.7v which is plenty to power an LED/s

3. Charger.
I used this charger from eBay. 

4. Mercury Switch

5. Female 3.5mm power jack

6. Male 3.5mm plug

7. Copper wire.
(To make the frame)

8. Clear casting resin. 
This can be purchased from your local hardware store or eBay.  I used "Diggers Casting Resin" which I purchased from my local hardware store.

9. Solder

10. Casting mould. 
I used a small, square, plastic container which held chicken stock cubes - see below


1. Soldering iron

2. Pliers

3. Wire cutters

Step 2: Creating the Frame

Picture of Creating the Frame

The first thing you need to do is bend the copper wire to make frame.  One end is added to the battery terminals, and the other to the female jack which is how you will charge the batteries.


1. Bend and shape the wire as the below images show

2. Solder each wire onto the battery terminals.  Make sure that once they are soldered onto the terminals, the battery sits flush and the wires are reasonably straight.

Circuit Board - Make sure you mark-out or memorize where the wires are connected the circuit board and switch - you're going to need to make sure that you solder everything in the right place and on the right polarities!

3. Cut a small piece of copper and bend as shown.  Attach to one of the battery solder points on the back of the circuit board as shown.  This will be where you attach the circuit board to the frame/battery

Step 3: Adding the LED’s and Mercury Switch

Picture of Adding the LED’s and Mercury Switch

Next thing is to add the circuit board which has the LED's attached, and switch.  Be careful – you don’t want to break the mercury switch!


1.  First you need to solder the circuit board onto the battery terminal via the small arm attached to the circuit board as shown.  This is a fiddly job and may take a couple of tries to get straight.

2.  Next bend another small piece of copper and solder to one of the solder points where the switch is attached.  This copper arm should be sticking-up as shown below.

3. Solder on the mercury switch.  As you can see in the images below, I have slightly angled the switch which will allow the mercury to move significantly enough to turn off the LED’s if they are turned on their sides.

4. Solder on the other switch wire to the end of the mercury switch.

5.  Solder the last wire to the other battery terminal.

6.  Add the female power jack to the ends of the copper, making sure the polarity is correct.  This is your chance to shorten the copper if necessary.

6.   Test.

Note – I’m sure that everyone is aware that mercury is very poisonous.  Please be careful when handling it and use the usual precautions.

Step 4: Testing the Resin

Picture of Testing the Resin

I decided to do a test first as I didn't want to mess up the LED's and have to start again!.  Instead of the LED's I added a battery to the resin (first thing I found lying around).  When mixing the resin I found that it starts out with a slightly yellowish tinge but once it sets turned clear.

I left the resin to cure for 24 hours and then removed from the mould.  I had to break the mould to get it out and then leave for another 24 hours until everything was completely dry.  The finish on the hardened resin was rough but clear.

I used some 600 and 1200 wet / dry sandpaper to get some of the roughness out of the casting and used some brasso to give it a really smooth finish.

I initially tried to create a hard, resin base and let that set but I couldn't wait so I just poured the whole of the resin into the mould.  If you look at the images, you can see a faint line where the 2 different set resins meet-up.

The steps on the following page show how to achieve a clear finish using wet sandpaper

Step 5: Adding the Resin

Picture of Adding the Resin

Now that you have finished your LED light and switch, you now need to put it in clear resin.


1.  First you need to decide on what container (mould) you want to use.  I found the below container at the supermarket which worked perfectly.

2.  I decided to use the lid as the base as it was smooth and would also help to get my cast out easier.  Cut the top off the container so you can pour the mould in.  I then hot glued the up-side-down lid to the opening.

3. Add the LED’s and battery to the container, making sure that the socket it at the top! (obviously) and add some blue-tack to the hole.  This way you won't get any resin in the jack.

4. Mix the resin as indicated.

5. Pour in the resin to the top of the jack.

5. Set to dry for 24 hours and remove from the mould once finished.

Step 6: Smoothing and Finishing

Picture of Smoothing and Finishing

Once you take out the cast out of the mound (I had to break the mould to get it out!) you’ll have to polish the cast to get a clear, smooth finish.
I must admit I didn't what wet sandpaper is and how it worked.  After some research I discovered how to use it correctly.  I have put together some points below for these like me!


Wet sanding is a sanding technique that uses water to lubricate both the sandpaper and the surface to be sanded so the grit will last longer, and so you can attain a smooth-as-glass appearance. Using water while sanding will also keep the dust down.

1. Soak sheets of sandpaper in a bucket of water for 20 to 30 minutes before using them. Start sanding with a low-grit paper (300 grit) to remove large imperfections quickly.

2. Take the sandpaper out of the bucket and cut it to fit around a rubber sanding block. Wrap the sandpaper around the sanding block. Avoid wet sanding without a sanding block because your fingers will press onto the sanded material unevenly, wear the sandpaper out faster in those areas, and it may take longer to obtain an even sanding.

3. Spray the surface to be sanded with water, coating it evenly. The water will hide the scratch, so you will think it is gone when it isn't. Clean the water away from the area to see if it is really gone before moving on to other areas.

4. Sand the surface with progressively higher grits. Sandpaper is available in grits up to 4000, but it is OK to stop sanding after using 1200 to 2000- grit sandpaper.   Clean the surface in between grits to remove debris so the finer sandpaper is not contaminated with larger debris. Spray water onto the surface as needed.

5. Add a buffing compound such as Brasso to the sanded area when sanding has been completed and buff the area with a cloth.

Step 7: Finished

Picture of Finished


You now should have a pretty solid looking clear resin cube with an LED embedded inside.  Try it out and make sure that everything works ok.  If it doesn’t I’m afraid there isn’t much you can do but start again!

I found using resin pretty easy - as long as you follow the instructions you can't go wrong really.  It’s a great product and I can't wait to use it again.


The next one I make I don't think I'll use the female power jack.  Solar would work better and everyting would be contained inside the resin.  You would need to find a small (and I mean small!) , 4.5v solar panel but it would be pretty cool.
You could also have 2 peices of the copper sticking out of the top and when you need to charge you could connect a 4.5 solar panel to the ends.  This would be a good way to simplyfy the insides. 

Happy casting.


magiceye (author)2015-05-22

I have a mercury switch connected to 12v bulb I am going to give circuit a try thanks to your instructable.

benom (author)2015-04-11

I have done a resin cube with a small solar cell. It was working fine, but after a week it's not working, I think that the battery has died :(

bassam.alzoubi (author)2014-11-24


what's the type of the mercury switch .??

Flambout (author)2013-05-21

This is so cool. I have bought the components to build this with a solar cell; but I do have a question. How did you keep the battery and the copper frame from being exposed to the air? If they were sitting on the floor of the mould, I assume that the resin could not entirely cover them. Did you manage this?

webgiant (author)Flambout2014-03-30

One way of preventing the bottom of the apparatus from touching the base of the resin is to mix up a tiny portion of the resin and fill the bottom of the mold. Then once the initial resin is dry, rest the apparatus on the resin base and fill it the rest of the way with resin mixture. The heat from the second application of resin should bond the resin base to the resin block, as it has done for me in the past.

mrlivingston (author)Flambout2013-05-23

I'd really like to see your design with the solar cell, can you share some details?

Flambout (author)mrlivingston2013-05-23

I have not had the compenents delivered yet. I was planning to copy this one, but wire up the solar cell to the batteries. I don't know wherebouts you are, but I bought a torch powered by a solar cell from the UK store Maplins - the brand name is Rolson and it says the cell is rated at 4.5v. The cost was about three pounds or so.

lonesoulsurfer (author)Flambout2013-05-23

Are you going to incorporate the solar cell into the resin? That's definitely the right way to go. I haven't found the right size solar panel yet, I'm looking for something small and square.

Also, you'll need a 5v to 5.5v to charge the 3.6v battery, the voltage needs to be higher so it is "forced" into the batteries.

Flambout (author)lonesoulsurfer2013-05-24

Ah. I was hoping that a 4.5v cell would do it. Do you think that would work or shoudl I source a better cell? If it matters, I would prefer a low rate of charge to the battery since I think the cell will be exposed to light pretty much 24/7, but the LEDs will only be on occasionally. I am a bit worried about overheating.

lonesoulsurfer (author)Flambout2013-05-27

It might be ok - I assume the batteries are 3.6V? Overheating could definitely be an issue but so far my one hasn't exploded! It has probably helped that the batteries were so close to the bottom of the resin!

Flambout (author)lonesoulsurfer2013-05-28

Yes, the batteries are 3.6v. I was wondering whether it is possible that the power jack in your cube could be acting as a heat sink? I assume it would not be very effective but it is connected to wiring, so any heat would presumably go along the metal of the circuit to the air.

I was thinking about resting the battery on a coin with the coin acting a a heat sink - what do you think?

I haven't made it yet! I plan to do one in a couple of weeks though. It will be similar to the one I made bit will have the copper sticking out the top so you can charge when needed.

lonesoulsurfer (author)Flambout2013-05-22

Good spotting!
There was a thin layer on the bottom and the battery was just inside the resin. Once I started sanding a tiny bit of battery was exposed. The way to fix this is to put a small layer of resin on the bottom of the mould and let this dry. You'll then be able to put the batteries on top without them being exposed at all.

Happy building!

ccronkhite (author)2013-10-28

Another option for charging would be to extend copper wire out of the resin, trim it off and make it flush with the outside and have a charging base with contacts that it sits on.

webgiant (author)ccronkhite2014-03-30

Or a snap-on base containing the battery. The battery contacts sit on the very outside edge of the resin block, and insert into the snap-on base. This would remove the problem of the battery getting killed by the resin, and remove the need for the ugly DC port on the top by moving it to the bottom.

ccronkhite (author)ccronkhite2013-10-28

I like the bare wire. I'm picturing a steam punk inspired creation with copper wiring and a charging base made out of wood, and/or brass.

ruguberto made it! (author)2014-02-09

Hello i did my best, mi recine went really wrong XD

either way it gets to hot when getting hard, so i think thats why batterys fail

i am going to try a new one, hoping it gets better

lonesoulsurfer (author)ruguberto2014-02-09

Bad luck! Looks like though you got the insides to work which is great.

It looks like you have added too much catalyst to the resin. I have done this also before and the resin gets very hot and cracks. try using less catalyst next time.

Also, I would suggest trying my latest resin cube which can be found here. The batteries on my original don't hold a charge much any longer due to the batteries being enclosed.

Let me know how you go with the next one

ruguberto (author)ruguberto2014-02-09

Forgot the proces jejeje my recine its really not that good

bpark1000 (author)2013-12-06

Comment about casting resin around rigid objects: the resin is very hard when it sets. As it sets, it shrinks, squeezing what is inside. (In other instructable for cube LED, you mention battery failing. This is probably due to its being crushed by the resin.) If you were to embed coins in the resin, the resin would crack after awhile due to the stress, at the edges of the coins. 2 ways to deal with this. One is to have some material with give (dip the battery in silicone rubber). The other is to anneal the resin, but the heat would ruin the battery. You may see cracks in time around the heatsink in the embedded lightbulb instructable.

If you polish your cube (or wet it to temporarily to "cover" the scratches), you can look for the stress by putting the cube between 2 layers of crossed polarizer film (get it from a pair of cheap polarized sunglasses.) You will see dazzling color if there is stress. For non-battery cubes, you can anneal them at 250 degrees F for 24 hours, then slowly cool. Don't run cube until totally cooled. Avoid large rigid objects in cube, and objects that are long and thin.

nerd7473 (author)2013-10-20

I didn't read all of the instructable but what type of resin did you use or what type do you recommend?

sercancer (author)2013-10-16

Hi there!! It is very good instruction. Well done.
Ive got a question. I am thinkin to use this resin coating for my project. Is this copper skeleton essential? Thanks in advance

superdave5481 (author)2013-06-14

Most excellent! I am really fond of led lights and have a good many saves along with tiny ciruits to drive them. I think i might give this one a try. Perhaps a flikering candle and a color changing one with removable battery compartments on each to skip the need to charge. Going to the Dollar Tree, I can get many cheap batteries and leds. I got 4 finger lights for one dollar, each having 3 batteries. I got tiny solar garden rock led that has a small rechargable battery and a switch. I might skip the mercury switch also, even though it is a really cool idea. A really great job, thanks for posting this instructable.

jcduplessis (author)2013-06-06

They look excellent! Have to try this. Thanks!

lastchance (author)2013-05-30

cool project. i see alot of people asking about solar power and stuff. please do your research before just thinking adding a solar is an end all. in beam robot we have whats call a solar engine. solar engine are design to be as efficiency and reliability as you need them but each one as pros and cons. i would say try a D1 solar engine. it charges during the day and run during night,

gmz_daniela (author)2013-05-02

what did you use for the circuit board?

gmz_daniela (author)2013-05-02

where did you get the male 3.5mm plug?
and how long did it take you to build?

HarryBeast2000 (author)2013-04-27

Does this automatically stop recharging?

It takes a few hours to charge but doesn't stop automatically. It won't matter though if you leave the charger in, the battery will just get a bit warm but won't overcharge.

hazeshadow16 (author)2013-04-28

Where do I get the circuit board?

Check out the list of parts - its the first one. Actually you could use any type of LED light, as long as it has a momentary switch to turn it on.

zappenfusen (author)2013-04-25

Neat! May be my project for Christmas 20113.

pakito15191 (author)2013-04-21

When you said "You can see a faint line where the 2 different set resins meet-up", is it only on the surface, or does it go all the way in? (would it be possible to wet sand it?)

Hey there.
It is both - on the surface and inside. You can sand the outside one away so the 2 blend nicely. The inside can be just made out but you have to be looking for it to see it.

junits15 (author)2013-04-16

How cool would this be wi an induction charger

bowlen199 (author)2013-04-08

looks great, you could try and make it charge through induction. like a toothbrush

sirbow2 (author)bowlen1992013-04-14

^ +1 i was thinking the same thing!

shadowwynd (author)2013-04-08

This is a great idea and a good instructable. It has a lot of potential for variation.

You could also experiment with reflectors or diffusers in the resin above the LEDs. LEDs are very directional, so the light goes straight up. How would it look if you slowly added glitter or sequins while pouring the upper half of the resin? What about small squares of aluminum foil? What if you made bubbles in the top half (can of compressed air, or blowing through a straw)? What if you put a ping-pong ball (as a diffuser) directly on top of the LEDs and then covered the whole thing with resin? etc.

I would also vote for a different charging design (as you yourself noted). The female port on the top loses a lot of design points and can be accidentally filled with dirt, debris, water, etc. Inductive charging (like Wyle_E mentioned) would be the most elegant way of charging, but also the most complex. You could always just go with some copper terminals (pennies?) on the bottom that poke through the resin.

The resin kind of acts like a diffuser so the light gets reflected somewhat. The light from the LED's made some really intersting pattens through the pre-polished resin so definitey think there is opportunity to get some great effects. I saw a guy on Instructables use tiny silver stars in his resin and the effect looks great. bubbles too would add some great effects.

Agree with the improvement on the port out the top. You could use copper out of the bottom but you would need to build everything upside-down so the copper sticks out the top.
I would really like to enclose everything on my next design so I'm thinking solar panels. (trying to keep it simple)

Ahh another very cool idea with solar panels !

Ask and ye shall receive lol ! :

Solar Panels (DIY Style!):

Also you will need the tabbing wire:

could make up your own panels depending on how much voltage you need !

been keeping me eye on these solar panels lol !

there are also smaller solar panels already made that you can buy but my thinking was if you were going to encase everything in resin anyways, then these panels would be much smaller that an actual panel pre-made, but then there are very small panels pre-made out there ;-)

Enjoy ;-)

thomathome (author)2013-04-12

incorparate some wierless charging, a shake charger or solar? your in for a winner. they'd be waterproof and would look nice around the garden. keep up the good work i am of to order me some resin : D

spyder2021 (author)2013-04-07

Thats cool, like how it shows everything perfect. I have casting resin also, just have not used it yet. Don't know what to make. Only down fall is if the LED burns out for some reason.

The resin I have is I think "Clear-Lite" what brand do you have?

Hey there,
I used a casting resin called "Diggers casting and embedding resin" It uses a catalyst to activate the resin. I found it really easy to use. i think as long as you get the mixures right then you shouldn't have an issue.

LED's (if under the right conditions) should last 50,000 hours plus! What will fail at some stage is the battery as they lose capacity to store charge over time. but I reckon I've got a few charges yet before that happens : )

Wesley666 (author)lonesoulsurfer2013-04-07

The LEDs are of no concern, they will shine on and on for a good long time. The battery life will become short after awhile, which is why, SUPERCAPS! As I recall, caps can be recharged indefinitely over and over again, eliminating the recharging/battery life problem. Based on the size, the cube may need to be made bigger to accommodate a few of these bad boys;

But then add in a "wireless" recharging system. Maybe scavenge one from an old electric toothbrush? They charge through induction. Or get 2 identical semicircular ferrite cores. Wind a coil around one, a coil around the other, one goes in the resin and just the edge of the ferrite core is there, flush with the surface. Put a magnet in the resin, a magnet on the other ferrite core so they stick together and run AC through the outside cores coil. If you looked from the top down there would be a ferrite core/toroid, a circle, half inside the resin, half outside. Essentially make a transformer where you can separate the primary and secondary and the secondary in the resin.

lonesoulsurfer (author)Wesley6662013-04-08

Man - heaps of ideas! love it. looks like I'm going to have to get an electric toothbrush and start pulling it apart ; )

Just a quick btw !

check this out for the wireless charging components, really cool idea Wesley666, ive been thinking about using this wireless coil for a few projects !!!

Enjoy !

Just purchased one! really cheap air freight (I'll probaly have to wait 3 weeks though!)


I was going to suggest looking at the Qi system (~$70 2-position charging station + ~$10+ for hackable receiver modules) but the iMall product is waaay cheaper. Can anyone vouch for them working well, and for iMall in general?

Yaa i Love those professionally made wireless chargers but along with them comes a hefty price tag lol !

Anyhoo i will be buying from iMall in the near future, they also make PCB's for us home-brew tinker'ers but i dont think i'll quite have the money to buy from them in the near future, plus it looks like they are based in china and urge you to use DHL/Fedex shipping as opposed to regular air mail, which bumps the price up alot, still way cheaper than QI tho, lol ;-)

Will post my results when i do get hold of one of these tho ! Planning on charging my cell phone and arduino !

Wesley666 (author)lonesoulsurfer2013-04-10

The only thing about the toothbrush, they have that little knobby that sticks up, I don't know if that is needed or that helps hold the toothbrush on the base. Would be nice to have just a pad you set it on. If you do take an electric toothbrush apart, lots of photographs and documentation! I would (and I am sure many other would too) love to see whats all in there.

About This Instructable




Bio: I've always liked pulling things apart - it's the putting back together again that I have some issues with.
More by lonesoulsurfer:Display Frame With LED'sSimple Mini Fire PistonLightning Detector and Counter
Add instructable to: