Yes - that is exactly what I thought I need to copy some plastic parts or own creations !:
thanx for the howto - I read some before but this is a great step-by-step tuto !
I tried some liquid latex before:
but that's not the right choise - 'cause it has to be made layer after layer - and it was not dimensionally stable !
Then I tried a copy of the "42387px1" for my daughters trainset with modelling clay and kind of resin - works fine, but that's an realy easy lego-part.
So I decided to make it with TWO PART MOLDS...
I hope I'll have time to make something about it, soon.
Please let me know if you're having success.