# Geometric sculpture from 72 pencils

George W. Hart is a sculptor of constructive geometric forms (and writer of the Math Monday columns at Make), and I've long been an admirer of his work. Reproducing his art is far from trivial - I once tried to build his Chronosynclastic Infundibulum, but broke so many CDs I gave up in disgust. However, I recently discovered that Alejandro Erickson, instructable-r and self-confessed mathemagician, lives in the same city as me and runs workshops on geometric construction, so we hired him for an afternoon. He was the great geometry guru we'd hoped he'd be, and he kept 6 kids and 3 adults well entertained and busy making tensegrities. As a special request, he also taught two of us how to make a replica of Hart's 72 pencils sculpture (Hart made a limited edition of 19 unique examples of these). It took a couple of leisurely hours to build and glue, and with supervision was surprisingly easy to make. It can be assembled inexpensively using wooden pencils (\$5.74 for 72), a few rubber bands and a little superglue, in pretty much exactly the same way as Alejandro makes his Hexastix sculptures (see below for the video). The hexagonal cross-section of the pencils make them a very natural fit for this geometric form, as the holes in the lattice are themselves hexagonal. The erasers are arranged tetrahedrally with respect to one another; the volume enclosed by the pencils is a rhombic dodecahedron. It's a neat piece of art that I'm pleased to own; many thanks to George W. Hart for the inspiration and Alejandro for the instruction!

Video: Follow Alejandro's instructions, but build only as far as a hexagon consisting of a ring of 18 pencils, removing the inner pencils as you go. If you find the erasers aren't arranged tetrahedrally (as I did), just invert one ring one pencil at a time until your sculpture looks like the original. Superglue the joints before removing the rubber bands.

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alejandroerickson says: 1 year ago
Way to go! I'm so glad we connected and were able to do this. I want to add that I also sell kits to make mini versions of the coloured skewer hexastix in the video. Message me if the listing on ebay is expired.

If you live in Victoria, I would be happy to come do a workshop with you!
makendo (author) in reply to alejandroerickson1 year ago
Thanks Alejandro. Great workshop - thoroughly recommended!
MOMO100 says: 4 months ago
Awesome
hufan says: 5 months ago
I'm gonna try it tomorrow
craftmachine says: 7 months ago
great!
white dragon says: 11 months ago
can i use this as my cantamaths project in school???
makendo (author) in reply to white dragon11 months ago
white dragon in reply to makendo11 months ago
sorry i didnt catch that...could you please say it differently? THNX
makendo (author) in reply to white dragon11 months ago
"Sure"
white dragon in reply to makendo10 months ago
thanks you very much!
parmsco says: 1 year ago
I could not find 72 pencils at my house so I made it out of toothpicks and used rubber bands from when I had braces.
makendo (author) in reply to parmsco1 year ago
That's really neat. Thanks for posting it!
playfulplans says: 1 year ago
Wonderful- excellent work.
XP1 says: 1 year ago
Thank you so much for the Instructable and video. It took a while; however, I finally figured it out. Now I just need to get some Super-Glue.
makendo (author) in reply to XP11 year ago
Nice!
Zaphod Beetlebrox says: 1 year ago
Just like to let you know that I built one of these and that it works as a vary unique pencil holder.
mooner77 says: 1 year ago
would it be easier or harder to use straws?
makendo (author) in reply to mooner771 year ago
I think pencils are probably easier. Straws would tend to deform too much.
Chimex14 says: 1 year ago
HEY just btw, this geometric sculpture pencil thing made it to Failblog, and it was categorized as WIN!
It then made it to teh featured section of iFunny.
So kudos
Ppl think that u b epic
alejandroerickson says: 1 year ago
I've now made a puzzle based on this sculpture available on ebay:
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=250996113976
Here is an image of it (large version at http://geoburst.ca/ebay/chiastix/chiastixclose.jpg )
innovationcreation says: 1 year ago
I got super enthused and did not see the smaller note above the video saying

"Follow Alejandro's instructions, but build only as far as a hexagon consisting of a ring of 18 pencils, removing the inner pencils as you go. If you find the erasers aren't arranged tetrahedrally (as I did), just invert one ring one pencil at a time until your sculpture looks like the original. "

I had more than enough pencils but realized I used way more than 72... And I also noticed one axis set was not oriented correctly. And on my pencils, the pencil logo is not oriented in any consistent fashion. I figured out the removing the central core of pencils and re-oriented one axis.

Now to super glue...
makendo (author) in reply to innovationcreation1 year ago
Good work... yeah, having one the pencils aligned wrong is annoying but doesn't take too long to fix, fortunately.
AWESOME...no life?
Jealous?
Win Guy in reply to FlatLinerMEDIC1 year ago
Problem?
footbawl4life says: 1 year ago
bravo.
Xeriel says: 1 year ago
Will it hold precariously together without any glue or elastics, or does the whole thing fall apart?
makendo (author) in reply to Xeriel1 year ago
No, it would just fall apart.
EVM says: 1 year ago
Me and a friend made one and turned it into a pen tray by cutting out the middle and making a floor in it.

Thanks for the great idea

Greetings from the Netherlands
makendo (author) in reply to EVM1 year ago
Wow, it's actually functional now... nice! What did you use to cut out the middle?
EVM in reply to makendo1 year ago
We used the blade from a hack saw. The small pegs at both ends of the blade were grinded off with an angle grinder to prevent them damaging other pencils and we wrapped one half with band-aids so we didn't cut ourselves. In total it took 24 cuts
mrpesas says: 1 year ago
I saw this instructable and said "that's cool...wait...I have a box of pencils too" My students were very impressed with my "skillz"
makendo (author) in reply to mrpesas1 year ago
Bet they were, nice!
Win Guy says: 1 year ago
Makers gonna make. I am a maker.