Your first step will be to go here, download the CAD files, and 3D print them. I used a Makerbot Replicator 2 printing PLA using three shells and a 10% infill. Since these have long, flat bottoms and large, straight edges, you will want to add mouse ears, rafts, or other features to prevent curling and distortion. My method was to print each part using mouse ears on the corners, and then hold them down with the springs from the inside of laundry clips once the print head was high enough to avoid knocking into them.

While you're at it, you'll want to print out some Luer Caps and keep them to one side for later. Also, laser cut yourself a pair of these plates in wood or acrylic. The exact thickness of the plates isn't important, so long as they're strong enough to stand up to a little abuse.

Next, you'll need to gather all the tools and supplies.


  • Eco-Flex 00-50 - 1gal
  • Smooth-Sil 935 - 1gal
  • Sil-Poxy
  • Silc-Pig if you want to tint your robot (Optional)
  • Jewelry injection wax (I use the Freeman aqua wax)
  • Mixing cups
  • Tongue depressors
  • Nitrile gloves (Don't use latex... I learned that the hard way)
  • Paste wax
  • Chip brushes
  • 3" 1/4"-20 bolts x 6
  • 1/4"-20 wing nuts x 6
  • Luer fittings (These things are so useful. They form an airtight seal and are quick to assemble)
  • PVC tubing (Get the corresponding size for the Luers you buy)


These materials will run you somewhere around $300. However, once you’ve got the materials and molds in place you’ll have everything ready to make dozens of soft robots.

All the materials I’m recommending are safe to work around, though you’ve got to use common sense when using them. Work in well-ventilated areas. Wear a respirator if you’re chronically exposing yourself to solvents or vapors. Wear disposable nitrile gloves and change them in between processes. Don’t keep food, drinks, or things around that you could cross contaminate by touching with your gloves on and then touching again with your gloves off. Handling chemicals is a lot like handling raw chicken: it can be perfectly safe as long as you minimize the potential for contamination, keep good hygiene, and clean up after you finish.

Also, I tend to use Smooth-On products because I know their materials well and have worked with them for years. They're certainly not the only company out there for silicones and mold making materials, but they're the ones I know and trust. They've actually been nice enough to film some of these robots coming together and support the project with some free materials. So, I've got to admit to a bit of favoritism but feel free to experiment with other materials.

This guide was first published on Mar 24, 2014. It was last updated on Mar 24, 2014.

This page (Gather Materials) was last updated on Mar 21, 2014.

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