3D Printing! Mold-making! Digital Rendering! Apoxie Sculpt!!! Woodshoppery! For this project Tina and I decided to try to learn about 3D printing and I'll show you what we learned and how we ended up making the toy. We were asked to make two robot reindeer toys as props for a Christmas film; one is a retro, 1970s robot and the other is the updated sleek modern version. The legs and head have slight articulation and the nose has a red blinking LED.
Also; I'm entering this build in the 3D Printing Contest. If you like it please vote (up there in the top right corner) I would LOVE to win a 3D printer - holy smokes, how awesome would that be????!
Here are the materials that I remember using:
SLS 3D printing
Wood (3/4 ply, 2x4)
5/8 threaded rod
Spray paints and primers
Smooth-on Mold Star 30
The first step in the build was figuring out what it would look like. I scratched out some possible shapes and designs in my sketchbook and ran them by the production designer. As it turned out he was taken with one of the doodles and we went ahead with that design without changing it too much (mostly the antlers and the addition of a rocket jet pack on it's back). I hired a 3D renderer (Brad Rothwell, who has submitted some great stuff here on Instructables) to make a Solid Works rendering that I could submit to the printers.
Step 1: Building the legs and substructure of the torso
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OK, so here's the deal. 3D printing is an amazing new field but it still has some hurdles to overcome before it is appropriate for a job like this one. When I first emailed the design around to the local 3D printing shops in my city I was getting really amazing quotes like "it will cost a few hundred dollars and take 24 hours to turn around". Amazing! But.... not at all accurate. After hiring Brad to render the drawing into 3D CAD stl files I found out that the build would actually cost between $4-7 THOUSAND and that just the 6" front leg would take up to 10 hours to complete. All this information came a little late in the build and left Tina and I with about two days to figure out an alternate way to complete it.
After a lot of growling and mumbling by me we ended getting just the head done, using a 3D process called SLS from a company called Anubis. I have to say, I was really happy with the results. While still considerably cost-prohibitive for projects that could be done by hand with sculpting (the bill for the head was just under $600), the result was actually really great. I'll get back to this in a bit.
We printed the wire frame of the sketch at the size and I glued pieces onto 5/8 ply, cut them out with a scroll saw. Tina cut out the padded armor pieces from mdf and glued them onto the legs.
The torso was a shaped piece of 2x4 (we needed this to plug the legs and neck into later). Tina glued foam onto the 2x4 and shaped it by comparing it to the printout.
Step 2: Apoxie sculpt! Amazing stuff!
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We sculpted the armature for the legs and torso out of wood and foam, then we got to Apoxie Sculpt. If you're reading this then you are likely someone who is interested in building weird little things too. YOU HAVE TO GO PLAY WITH APOXIE SCULPT!!!! It's awesome - it gives you a few hours working time and doesn't have that horrible chemical smell or the pore-embedding qualities of plumber's epoxy. When it cures you can sand it and cut it and shape it but it's hard as concrete. Love it!
Anyway, we covered the legs and torso in it and then Tina went to town shaping it (she's much better than I am at sculpting). She just kept comparing the piece to the printout, then to the opposite leg, and just kept working at it until they looked manufactured. I was quite impressed, if I may say so.
We joked that the torso looked like a cooked concrete chicken. Eventually that's all I could see, a chicken torso.
Step 3: Molding the nose, painting the legs.
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The nose had to blink and the 3D-printed one was an opaque white piece. I sanded it, glued a stick onto the back and then poured a mold of silicone around it. I used a clear resin with red tint mixed in and after it set I cut off the extra bit. I drilled a hole in the back for the LED to sit in. Tina soldered a resistor and battery pack onto it and I apoxied it into the head. There's a button under the jaw to switch the light on.
I hit the legs up with a light coat of primer, gave them a smooth sanding and then a considerably thicker coat of glass brown. The trick now is to let them sit for almost two days without touching them (fingerprints!!!).
Step 4: Finishing
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Something I learned about Apoxie Scult - you CAN use water (a damp finger) to help shape but DON'T soak the material in water or it loses it's strength. Some of the parts I sculpted with too much water involved crumbled with a bit of pressure and Tina had to go back, cut them out and refill them (hard to do under a tight deadline because it just adds hours to the cure time).
I glued the 9V battery pack to the inside of the head. I had forgotten to request a lip along the seam and structural gussets inside the head rendering so the piece, which is only about 1 mm thick, was tough but pretty wobbly/flimsy. I ended up sculpting a lip to be able to glue the jaw and upper head together. I also made a 'brain' out of three pieces of layered plywood. This gave me something to drill the neck into and added some rigidity to the skull.
Step 5: Finished!!
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And that's it! If you have any questions or would like clarification on any of the processes please leave a comment!