Polycaprolacton  (also known as InstaMorph, ShapeLock and maybe other brand names) is a plastic that becomes workable at 150 deg. F. It's hard at room temperature. It's a great material for inventing and prototyping. This Instructable shows you how to make plastic bolts. I made a 1/4 inch bolt for these instructions. I think this is close to the smallest bolt you could make with this material and process.

Step 1: Gather Materials

Picture of Gather Materials
You will need.
  • 1 x 1/4" bolt
  • 1 x 1/4" nut
  • a source of 150 degree heat. (stove, microwave, hot plate)
  • 1/8 - 1/4 cup Polycaprolactone pellets
  • Thermometer (optional, but handy)
  • Waterproof work surface that won't stick to the Polycaprolactone.
  • Sharp knife or razor blade.
You have many choice for a heat source. A pot of water on the stove works well. You can use a microwave, but I find it to be a pain to keep heating the water all the time. I used a $32 electric skillet with a heat control. I was able to "dial in" 150 deg. F. exactly and hold it there. For other projects I have used a heat gun. Be careful if you use a heat gun. It's easy to overheat the Polycaprolactone or get the bolt scorching hot.

You don't have to use a 1/4" bolt exactly. Any nut and bolt that match could work. I don't think you can make a bolt much smaller than 1/4 inch that's very long and works.

Polycaprolactone will stick to plastic, so test a tiny bit on your work surface before you get going. If you overheat Polycaprolactone it gets stickier. That's a useful trick for other projects, but don't let it get over 150 deg. F in this project.
Chanio3 years ago
Good! I like it!


You said that it sticks on plastic.

Does it stick also on Polycaprolactone pieces?

What I want to know is how do you prevent both parts of the mold to stick together?

And also, how do you prevent the mold from sticking with your project?

I have also worked with molds before, and used to make some protrussions on the first mold in order to make the second part attach exactly on the first one.

In order to achieve this perfect attaching I needed to cover the first mold with some liquid soap or oil to prevent the second mold from sticking with fhe first mold...

Your molds should be pretty accurate to work well. How do you do this?

Thank for this great idea!

dustinandrews (author)  Chanio3 years ago
The shapelock (or whatever brand you use) won't stick very well to itself unless both pieces are hot. So if you have a cold piece and a hot piece, they snap apart as soon as it all cools. Thus my mold technique needs no release agent.
It also won't stick to plastic at 150F (usually). But it will stick like crazy (to plastics) around 180F.

For registering the molds I just relied on the unevenness of the surface of the first half. They second half snapped right into place.

The molds were accurate enough for the screw, but I did touch it up at the end with a metal nut.
WWC3 years ago
Clever. I have never seen this before, very useful.