Working with Polymorph / Shapelock

Late Saturday night I played with some polymorph plastic.  You can heat this plastic up in hot water and it melts into a dough like form, and sets hard again as it cools.  It is very easy to use and very strong.  An excellent material for prototyping.  I also think it is a good material in its own right.  Mechanically it is very slippery and resilient to flexing.  You can use it thick and rigid, or purposefully very thin to create flexible joints.  I thought I'd share some tips on working with it.

Notice some clay trapped within the polymorph.


  1. Using hot water means the polymorph will get wet.  Have a tea towel on hand to dry the plastic off as you pull it out of the hot water.  A tea towel is good because it is not fluffy!  Fluff sticks to polymorph.  I lay the towel flat on the table and press the polymorph into it.

  2. If you can be a bit patient, I find polymorph can get really extra soft and squishy if you leave it in boiling water for longer.  

  3. Big clumps of polymorph don't melt well.  Initially it is in granular form, but one of the good things about polymorph is being able to reuse it.  Whenever possible, stretch any excess polymorph out thin before it cools, it will be much easier to re-melt. 

  4. The downside to stretching out polymorph is that when you reheat it, you will need to fold it to get thickness back.  This is a really difficult stage, where water can get caught between layers.  Try to dry out your polymorph properly before folding.  Better yet, take the time to cut your polymorph up into tiny pieces before starting work.  

  5. Hot polymorph cuts really well with scissors.  Scissors are my favourite way to get clean edges.   Because it melts when it gets hot, any tools that create heat through friction are a bit more tricky to use.  The plastic tends to stick to the tool.  Scissors slice through nicely.  

  6. In a similar way, you can carve with a stanley knife, but this is quite dangerous.  Polymorph is self-lubricating and very slippery.  Its usually naturally creates organic shapes which are hard to carve down.  It cools to a very hard object, so the blade is prone to biting in only to suddenly jump out and into fingers.
  7. oops

  8. Polymorph is reasonably easy to puncture with something sharp.  I like using a throwing dart, as you can get a good grip and the dart point has a good taper to widen holes.  However, the polymorph does seem to close up on itself.  So use something like a dart, and then a drill bit by hand to cut away the hole a bit more.   

  9. If you can, work in details like holes and clean edges with tools whilst polymorph is a bit soft.  It is much much easier. 

  10. You can add threaded holes to polymorph for screws!  Simply, whilst the polymorph is hot, place a screw through the plastic and ensure the polymorph has a good grip on the screw.  Once set, unscrew the screw and you'll have the negative threaded hole left.  This is a good way to avoid using nuts on your screws, and to create boxes or access ports in objects that can be secured. 

  11. Polymorph only seems to stick to itself it both bits of polymorph are in their hot and malleable form.  It you shape hot polymorph against cold polymorph, the two can be pulled apart really easily. 
    1. This can be a bad thing if you need to extend some work.
    2. I've not tried it, but it might mean you can create a mold from polymorph, and then use more hot polymorph against the cold mold to cast a replica

  12. When combining two bits of hot polymorph, the seams can be hard to blend and flatten out.  By far the best strategy I've come across so far is to have something solid to push against.  In most cases this means working with a mold. A mold could be a custom made plaster cast, or an ordinary object that meets your needs. 
    1. With a mold you can get very smooth surfaces on the polymorph.  Working by hand leads to finger depressions and organic surfaces.  Either could be useful.
    2. When using a mold and pressing in your polymorph, use a pair of scissors to cut away the excess overflowing polymorph.  I found a scalpel didn't work so well.  

  13. When using polymorph against objects be really careful with any other dirts or foreign objects.  I pressed polymorph against an object I sculpted out of clay.  The clay got between layers of polymorph, which made it really weak.  
    1. Interestingly, the thin layers of polymorph showed the clay, giving it a new colour.
    2. Also, these many separated layers of polymorph gave it quite a good degree of flexibility, and could be a nice way of rendering joints.
    3. Trapped dirt is really hard to later remove from polymorph, and can ruin your otherwise reusable stock :(

  14. Lastly, I had a brief experiment with a hot air gun (paint stripper).  This was really exciting.  The polymorph seemed to retain its hot flexible state for longer.  Also, it wasn't wet!  I used the heat gun to heat up a piece of work to make some adjustments.  I'll be doing some more experiments here - I'm not sure what will happen if the plastic gets too hot.  But this could be a good way to keep polymorph flexible for longer, giving more time to play.