A few years back I was taught how to make a replica of George Hart's 72 pencils sculpture:

Here, I've remixed this idea to make a variant sculpture. It now uses 76 pencils, but this time they're arranged as four interpenetrating six-pointed stars rather than hexagons. It cost about $11 and took about an hour to construct. It's easier to make than the original, because there is no need to replace the pencils as you go - they are all placed in their final positions. The 28 and 52 pencil versions of the sculpture are also quite nice, if you don't have enough pencils for the 76 handy.

Step 1: Materials

You need 76 pencils and at least 60 tiny rubber bands. If you want to make your sculpture permanent, you will need some superglue. I used a pack of mixed coloured pencils (~$10) and a Rainbow Loom a few Rainbow Loom-style rubber bands (a few cents). I decided to divide the pencils semi-randomly - each of the four directions would be reds/pinks, yellows/oranges/browns, greens, and blues/purples. You need 19 pencils for each direction (one central one, and three rings of six).

Step 2: Initial Assembly

I've included Alejandro's video below because it really nicely shows you how to do the first few steps of the build, which are the tricky ones. These are made up of groups of pencils pointing in four different directions (tetrahedrally arranged, for those interested in geometry, which means each pencil is either parallel to or at 109.5° to the other pencils in the structure). I chose to aim all the points upwards, so the sculpture has a maximally spiky exterior, but arrange how you see fit.

Start by making a group of 7 pencils. Put a rubber band around them. Take two pencils, and split these into 2:3:2, and do the same with another two pencils in a different direction. Repeat to make two layers of two pencils in each direction. Put rubber bands around all ends. Now place the pencils on the table in a three-legged stool, and look straight down, trying to find an arrangement where you can see four hexagonal-shaped holes. Put pencils through these, and rubber band each end.

Step 3: 28 Pencils

Complete 7 pencils in a ring around the central one for all four directions. Replace the encircling rubber band with three securing three pencils in a row at each end. This helps keep the central pencil in place. This trick isn't shown consistently in the photos, because I didn't figure it out until later in the build.

Step 4: 52 Pencils

Now add another pencil in positions radiating out from the center, securing each one as you go with a rubber band that goes around three pencils in a row. You won't be able to do all six in each direction until you have added extra ones in other directions; just work your way around slowly. You've done all the hard stuff already.

I actually quite like the 52 pencil sculpture. You may just want to stop at this point rather than add the final ring.

Step 5: 76 Pencils

Repeat the previous step, adding a new rubber band for each pencil. And you're done!

You can make your sculpture permanent by supergluing the joints and removing the rubber bands. The sculpture may look like it should hold together by itself, but it won't. Don't take my word for it, though - you should try it yourself...

To encourage you to make your own, I'm offering 3-month pro memberships to anyone who posts "I made it!" pictures in the comments section.

The one on the right we made last year but since we didn't glue it it started to fall apart. So we made another one just now and made it the full size. Now we just need to glue this one. <br>Great project idea. Thank you for sharing it with us.
<p>Nice! Mine also fell apart when the bands perished and the kids tore it apart for the pencils.</p>
how long will you do the pro memberships? I plan to make one soon
<p>Great! There will be one waiting for you.</p>
Thanks! :) I need to buy more rubber bands
Can u use crayons
<p>Any cylindrical object would be fine, but the shorter and stubbier they are the less rings you'd be able to make. 28 should be easy enough with crayons.</p>
fun! quick and nice project !
<p>Nice! Thanks for posting the picture. 3 month pro on its way - sorry about the slow reply, I haven't been getting notified of messages...</p>
<p>I learned this general sort of construction from Dr. Charles Schwartz at Rider University several years ago. I have made a number of things related to this one, but had not made this one before today. I used a little different process than in the 'ible, mostly because I had longer rubber bands at hand.</p>
<p>Nice, thanks for posting! (3 month pro PMed)</p>
This is pretty darn cool! I plan on [trying to] make it [one of these days]...
<p>You should. The first part is a little tricky, but it's pretty easy once you've got the four directions sorted out.</p>
One day I'll try and make one :) think I will use an all natural pencil. Plus, I like how you color coordinated the rubber bands with the color pencils. Nice attention to detail :) Good job.
<p>Excellent stuff, my friend. Very cool project. </p><p>I think I need to get box of pencils and some rubber bands for my chronically "bored" 11-year-old, and show him this. Will post a photo if he makes one!</p>
<p>Thanks Sam. Yeah, it will keep him busy for sure - expect a few thrown missiles during the figuring out of the initial steps, though...</p>

About This Instructable




Bio: Analog maker dabbling in digital manufacture
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