After seeing it recommended by /members/shabaz I bought myself some Polydoh. It's a low melting point plastic supplied as little spheres. You put it in hot water and it goes clear and moldable. I've used it to make quick covers for pin headers. It sets to a white hard but not brittle white plastic wehn cold. It can be written on with a suitable (indelible) fibre tip pen.
Recently I had a different problem.
My wife's sister had bought some Victorian style bath taps but the bezels supplied with them would not slide right up to the body of the tap as she wanted. So I said I would machine the bell shaped bezels, thinking it would be easy to open up the holes on a lathe.
Unfortunately I wasn't able to hold the parts in a lathe chuck, the outer face is not cylindrical and the chuck makes only point contact. If I put anything soft in to protect the polished metal surface the chuck just didn't hold.
The other day I realised that Polydoh could rescue me here.
I started with the bezels on a piece of model board (foamed poly-propylene that you can buy in sheets). The screws are to give the Polydoh something to key onto.
Then I moulded on the Poldoh.
Once it was set I clamped the model board up in the mill.
I used this nifty gadget to find the centres of the existing holes.
And then the mill could do its bit.
I poured boiling water into the bezels and that softened the Polydoh enough for me to be able to pull them out.
And fit them to the taps:
(You can buy the same stuff in bigger bags and cheaper under the name "Whitemorph")
Blog edited for test purposes 11:07 am 02/02/2023