Release agent for casting of 3d printed part?

[Michael Morris]

I've bought a (quite expensive) very small 3d printed part for a modelling project I'm doing.  I'd like to use the same part on another project as well, so I thought I'd have a go at casting a copy with milliput using a Blue stuff/oyumaro mould of the 3d printed part.

I tried to make a mould, but one half of the mould hadn't worked.  Unfortunately the original part of the 3d part broke trying to get it out of the mould.  What I could do with is to use some form of release agent so that I can get the original out of a blue stuff mould without risking damaging it further.  Any suggestions?
Thanks

[Steve Noble]

It would probably be easier to cast it in resin instead of Milliput. You can get release agent. I had some in a small glass jar when I casted some parts. It looks like vaseline. However it's more for when you make a rubber two part mould and when you pour the second half of the mould it is applied to the first half so the two won't stick together. If you paint it inside your mould before casting you may lose some detail. 

Edited June 19, 2020 by Steve Noble