Truncated Octahedron Lightbox

A while back my wife saw an art exhibit with a large, cut shape with a bright light in it projecting onto the walls. It was a room-sized installation, but she loved it so much I decided to try to make something like it for her. Based on her pictures, I figured out the shape was a truncated octahedron, which is a polygon of alternating hexagons and squares.

TL;DR - Here’s the result:

My first draft was just the shapes and a geometric pattern that I cut on draftboard, but I didn’t quite know how to fasten the shape together, so I just left a thick border and used tape on the inside. It was still nice-looking though, and I had a random LED light string that I put inside.

For the “final” draft, I spent time to create brackets with the appropriate inner angles. I also updated the design to remove some of the “blank” space on the faces, and added a base to feed the LED cord out of. This time I cut the whole thing out of 1/8" basswood plywood.

With the prototype:

Lit up:

If you’d like to attempt one yourself, here’s the file: octahedron.zip (612.8 KB)

And some tips:

  1. The whole thing fits on 2 sheets of proofgrade material. I used Thin Basswood Plywood for both the contrast and strength, with the built-in cut and engrave settings. (I bet it would look pretty cool in frosted acrylic though)

  2. It took about 3 hours to cut each sheet. 2 of that was the border engraving. I think it was worth it, but you could save a lot of time by removing them.

  3. All joints are either hex-hex or hex-square. The angles are different for each, so the brackets are marked with another engraving.

  4. The tabs are cut to fit pretty precisely, but not press-fit. I was worried that too much pressure would cause the faces to break. You will want to add glue, and I strongly suggest a needle-tip bottle.

  5. Assembly is tricky. I planned out the tab layout before assembly and pre-glued one side into the panels. Then, for the full 3D assembly, I added glue to the other side of the tabs and fitted them together once panel at a time, using tape on the joints to hold them until the glue set. If you want to try this route, here’s what I did for the panels:

    1. All 5 cut squares with all 8 square brackets
    2. 2 hexes with 6 hex brackets, on alternating sides (A)
    3. 2 hexes with 2 hex brackets on one side (B)
    4. 2 hexes with 4 hex brackets and 2 square brackets on adjacent sides ©
    5. 2 hexes with 2 square brackets on one side (D)

    Start with a square, add hexes A and B on alternating sides. Dry. Add the remaining 4 squares, then dry again. Finally, add hexes C and D on alternating sides. Once those are assembled, there will be one empty square space with brackets to sit in the “base”

  6. Cleanup on this is a real pain in the ass without a shop vac. I did the design work for the second revision a month or so ago, but I procrastinated on the actual cutting because I didn’t want to clean the little bits up again. I got a shop vac for Christmas, so cleanup took minutes this time :stuck_out_tongue:

82 Likes

Very nice. Reminds me of the Faberge fractals that were floating around a while ago. I’ve been working on something similar ever since. Thanks for sharing!

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Lovely!!

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They had/have something like that at the PEM in Salem, MA. Very cool.

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Nicely executed. Got any in-progress photos?

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Great project!
Thank you for the generous share, and the detailed write up. :sunglasses:

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Thank you. This is lovely.

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Great looking piece.

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Love the end project. It is beautiful!

Thank you for sharing your file, and for writing everything up so nicely!

moved this to FLD since the design was attached/shared

Moving to FLD might adjust the licensing terms intended by @jsmith1 you regulars should probably ask first before moving to FLD

Thank you very much @jsmith1 for a wonderful share.

I have a backlog of projects, but will certainly add this one to the que.

Best wishes in 2020 to the wonderful creative Glowforge community!

2 Likes

Thank you so much for the wonderful design. I was going to give it a go today and realized the “octahedron-2” may be corrupted. Anyone else getting this error?
Capture

Nope. Opens fine in Inkscape and the GF UI.

i opened it in inkscape, tweaked it a bit (moved the elements closer together) and saved it. It opened fine in the GFUI. printing now

Just finished putting one of these together. (still need to add a light source inside). Kudos to you for designing something that looks great, is fun, and goes together relatively easily for a stranger. I especially like that you included a slew of extra brackets and labeled them. Thanks for sharing.

Edit: added some lights, needs more. Link to photos and videos

This is naked Baltic birch ( 3 mm) so plenty of scorch marks which I like.

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Beautiful! What type of lights did you use?

My wife noticed me looking at this over my shoulder and I may have a new project to do.

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Gorgeous

Very cool and thanks for open-sourcing your pattern!

The exhibit your wife saw was these folks, correct?: