Protodough Prototyping Design Plastic

By Jack Arcade

How much does 250 grams make? Melted together, 250 grams makes a solid ball about the size of an apple or baseball. It doesn't expand, so if you filled a cup with the ProtoDough, the melted blob will take up the same space or slightly less when all the air pockets are removed.

ProtoDough comes in a granular form (3.5mm pellets) and is available in 250g and is extremely versatile, completely non-toxic, light weight, paintable, drillable and machinable. ProtoDough also has high elongation points and is safe for hand molding.

There are several applications for ProtoDough including creating toys and mechanical prototype parts, such as brackets, housings, molds, etc. ProtoDough's best feature though is that it can be reheated and reshaped repeatedly. You can even add colors to it while heating to enhance aesthetics. ProtoDough is also very easy to use – just add hot water.

Working with ProtoDough

First, be sure to use non-plastic containers to avoid bonding – ceramic, metal or glass containers will do. Add ProtoDough pellets and some water into a container and heat it to 150°F. There are a few different ways you can heat the container:

  • Heat the container with water on a stove until boiling, then add the ProtoDough
  • Boil water in a microwave then add the hot water to the ProtoDough already in the container
  • For remolding, put the molded part in the container with water and boil them together on the stove to change the shape
Once you start heating the ProtoDough, wait about 2 minutes until it turns clear, or until it becomes soft and moldable. The temperature is not hot enough to cause a burn, but removing the ProtoDough from the container with non-plastic tongs and allowing it to cool before you start forming the material into cool looking stuff is recommended.

Melted ProtoBough
ProtoDough Jelly
ProtoDough Mold

The Science of ProtoDough

ProtoDough is made out of Polycaprolactone thermoplastic, which is probably the best material for building your designed prototypes.

Thermoplastic is composed of polymer resins that become a homogenous liquid when heated above a specific temperature. As it cools you can mold it, and once it has completely cooled, it turns back into a hard solid.

The materials are efficient and cost effective for manufacturing. If designed correctly, thermoplastic prototypes may be a suitable material to replace metals. Don't feel like thermoplastics are a downgrade to metal, because they typically have better fatigue properties than most metals and can tolerate larger deflections without deforming.

However, as the name implies, ProtoDough's "kryptonite" is heat. The material can be easily melted, and some thermoplastics can degrade in direct sunlight and have poor resistance to solvents. Thermoplastics, while strong, can also fracture under high stress levels.

Impressions of ProtoDough

This was my first experience working with a thermoplastic, and I was delighted by how easy it was to work with ProtoDough – it certainly met my expectations. I was surprised how quickly it melted. In my testing it took around 2 minutes for the pellets to change color and form, after which I was able to mold it into some really cool shapes.

Not happy with your first effort? Rest assured that you can remold ProtoDough. Remolding, however, can take more time as you are no longer dealing with small granules but with a larger piece of thermoplastic material. To make the process faster, you can keep removing the outer layers by heating with tongs so that the inner layers can come in contact with hot water quicker.

I didn't have to hurry, so I had plenty of time for hand molding my desired shape. If you are molding into a complicated design, you might need to hurry up a bit just to be on the safer side before it hardens.

Molded ProtoDough Nut
Molded Screw driver Handle
Screwdriver Handle

I recommend ProtoDough and because it requires zero electronics knowledge, even a beginner level hobbyists can indulge in some molding! I made some pretty handy stuff. What would you make? Let us know at [email protected].

Jack Arcade earned his master's degree in Mechanical Engineering from Santa Clara University. He specializes in the design and control of robots. Jack's interests include traveling, camping, trekking, river rafting, bungee jumping and mountain climbing.