So as part of another topic, there was this thought to motorise a policeman with his head turning.
I knew i wasnt going to be able to drill a hole right through the body, so I decided to make a mould of a figure, but lay a tube through the middle of him.
Step 1 was to make a mould..
this was a simple plasticine mould with wooden formers to keep it all in.
Then i built up the sides
Next poured in some silicone after first making some key indents so as the second part of the mould would have something to lock against.
Then it was a case of flipping it over when cured, smearing it with vaseline and pouring the second half. Splitting this apart gave me a mould to start the next steps.
I didnt in fact tie it all together too tight when pouring the resin, so quite a bit of flash, easily trimmed. Just as the resin was becoming thick, I inserted a plastic tube which would allow me to rotate the head when it was cut off.
With a bit of brass rod, and a servo driven by a simple arduino circuit, the head now moves side to side , so this policeman is always on the lookout!
You can see a short vid of the head turning here..https://youtu.be/Gya0hE-75mQ