Tag Archives: lasercutting

The Dodecahedron

The Dodecahedron is a character in the children’s story The Phantom Tollbooth by Norton Juster, adapted for the stage by Susan Nanus. ChildsPlay AZ, our local youth theater, performed it during their September-October season. As part of our community work, FabLab Tempe built the Dodecahedron puppet the troupe.

This post covers Development, Testing, Fabrication and a Bill of Materials. Cutting files are available on request.

The Dodecahedron is a precocious mathematical construct who meets Milo, the main character, at a fork in the road to Digitopolis. He is described as:

The DODECAHEDRON Appears, a 12-sides figure with a
different face on each side, and with all the edges
labeled with a small letter and all the angles
labeled with a large letter. He wears a beret and
peers at the others with a serious face.


Development

The FabLab Tempe team built a series of these Dodecahedron puppets that culminated in a stage-ready puppet and backup made mostly of laser-cut acrylic. They started as material and geometry sketches, then choroplast (a fantastic material for working fast) and tape tests and finally as glued, sanded acrylic forms with internal lighting.

Development started with a series of requirements from ChildsPlay’s producers and design staff, mainly that it be portable, lit internally and easy to don/doff because it’s onstage for two minutes and the 5 actors were each playing multiple characters.

  • Dodecahedron with at least six expressions as faces on geometry
  • 18-24″ diameter
  • Light and grippy enough for an actor to manipulate easily on stage
  • Lit from inside – LED per face, NeoPixel, etc lighting.
  • Rechargeable battery in object or on belt – internal is better as belt might be complicated during scene changes.
  • Strong enough to survive dozens of shows or cheap enough to build/repair multiple units.

Some elements investigated and rejected included a tensegrity structure instead of finger joints (to complicated) and materials other than acrylic, including HDPE (milk jug plastic), lenticular plastics and polycarbonate. We also descoped the design from the original Dodecahedron as labeling angles and edges and making a doffable beret were to complicated for a two minute puppet.


Testing Cycles

We iterated through a development spiral that started with the above material and scale tests. Following paper prototypes, 4 units were constructed. The first was a bright and fun choroplast scale rehearsal unit. This was followed by three in laser-cut acrylic, two of which were stage-ready. The final acrylic unit utilized onyx-black acrylic for the faces instead of spraypaint or vinyl stickers, both of which were investigated in testing.

The biggest issue encountered in testing was developing an appropriate handle and handle interface. One constraint was the puppeteer’s size and an injured shoulder. Another was the thinness of the acrylic. Initially the actress wanted a spinning knob on a small lazy susan bearing, but this didn’t provide enough leverage. We eventually came up with using a length of pipe, bicycle handlebar grip and PVC tube mounted on an electrical fixture (thank you, ACE Hardware). The bottom of the Dodecahedron was reinforced with a second layer of acrylic and painted.

Several lighting elements were examined, including a NeoPixel array with Arduino microcontroller, a USB light and glow sticks. The best light was a simple LED bulb from the hardware store. It was bright enough, cheap ($7) and simple to mount.


Fabrication

Fabrication involved many hours of cutting on AME’s Epilog laser cutters and staged assembly. Units were taped, then glued and hand sanded to consistency. Laser cut appliques of the faces were carefully plotted to match ChildsPlay designer Rebecca Akins’ specifications. SciGrip 16 adhesive was used for both the seams and applique. The stage-ready units were then trimmed with black electrical tape.

Photographer: Tim Trumble. The Dodecahedron on stage at Tempe Center for the Arts.


Bill of Materials

Special Thanks to Xin Wei, Connor, Skaidra, Jenn, Sarah, Dwayne, Rebecca and Anthony for making this project possible.

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Making Pinhole Cameras with a Laser Cutter

This is an old project from teaching at AS220’s Fab Lab Providence (now AS220 Industries). The premise was simple, to create a pinhole camera using the Epilog Minihelix laser cutter in the Fab Lab and shoot some pictures using equipment in the Paul Krot Community Darkroom. The cameras were made and used over two Saturdays in March 2010 with the fabrication class led by myself and the photography segment led by Miguel Rosario.

The cameras are unique for pinhole cameras in that they use reloadable film holders based on old large-format cameras. This enables them to be reloaded inside a black bag in the field. The film holders are sized for 4″x5″ film or photo paper. In the class, we used black and white photo paper.

The cameras largely follow Alan Kay’s concept of self-documenting software in that in cutting the files, the instructions are etched into the surfaces for easy assembly. There are also aiming guides etched into the top surface for lining up shots.


Download and cut your own! Pinhole Camera Class Files


Assembly instructions:

Materials: 1/8″ board, hot glue and glue gun, gaffer’s tape, scissors, utility knife.

Download files and laser cut them using your preference of materials. 1/8″ Foamcor, cardboard, plywood or MDF will all work.

Assemble the camera body by laying down base and attaching the front, sides and center divider. Attach the top cover. Hotglue all edges inside and out then seal over with gaffer’s tape or other light-proof material.

Take a small piece of copper, aluminum foil or copper cladding (3M EMI Shielding Tapes 1181) and place over the aperture on the inside front of camera. Tape it in place to guarantee a fit. Take a small needle or bobby pin and carefully poke a hole in the center of the foil.

Attach the back plate, glue and light-proof.

Attach the film holder cover with gaffer’s tape.

Make folding film holders from the two holder components and gaff.

Glue the two pieces of the lens cap together. Add the lens cap to the camera. It can be attached with hook-and-loop, tape or jammed into the aperture. Jamming it in place is not recommended for field cameras as it can damage the foil, but does work for practice assembly.

Insert film into holders, load camera and shoot to your heart’s content.

Orthographic promotional view of camera.
Miguel Rosario’s images, inverted to normal view.
Joshua Gigantino, negative images.
Cut file image, film holders.
Cut file image, camera body.
Laser-cut components in archival foamcor.
Student assembling camera.
Assembly.
Interior view showing gaffer’s tape seals.
Exterior front view.
Interior view without rear plate.
Student assembling a camera.
Student assembling a camera.
Film loading slot closeup.
Various cameras during development.

Overall this project was a real success. The workshop had only two students and two instructors but we all successfully built, shot and printed using these cameras. There is a lot of possibilities for combing these kinds of very old technology with digital fabrication.

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