As it worked so well I thought I'd have a go at something more 3D, so the natural choice was a key cap. And what do you know it worked (not brilliantly) first time believe it or not:
As you can see the results are very rough and ready, and needed a little file work, but for a first attempt was very good. I'm expecting much better results when I try with plasticine next time!
So how do you do it? Well you will need just 4 things; bluetac (although I think this will work much much better with plasticine, but I'm yet to try it), the cap you want to cast, really cheap super glue (because the cheap stuff tends to be really thin and fluid, which is what you need for this) and a cocktail stick.
Get the bluetac and make it into a big blob and then flatten the top of it, you then take the cap and run it under the tap (this is so it doesn't actually stick to the bluetac) and then push it all the way into the blob, then carefully pull it out again taking care not to deform the impression.
Now this the hard part, run the cap under the tap again and then push a large blob of bluetac into the inside of the cap so it fills it all up, then carefully remove it again taking care not to deform it, this may take a few attempts as getting the MX stem slot can be fiddly. If it does deform a bit you can gently pinch it back into shape.
Now get the first mould and pour the super glue into it, and pour a bit into the MX stem slot bit of the other mould and then assemble as shown:
It doesn't matter is it overflows as you can file the excess off.
Leave the whole thing for about a day to cure. After that all you need to do is remove bluetac, this bit is a pain is the arse and takes ages.
This helps get the worst off the outside of the cap:
And this helps get the worst out of the inside of the cap:
DO NOT use it on the MX stem hole though!
To get the rest off use hot water, a toothbrush that has had its bristles cut short and washing up liquid. The very last you can get off with another piece of bluetac.
So go on, give it a go!
