Dagorlad I really like the colors you picked for the rock. Did you use Styrofoam as a core?
Yac-formed styrene wont last very long as a mold But I think that is the Mold Popa Tom used in his school project video. You can get a good effect.
Quote:
Lubed it with Vaseline as mold release
Well, I am glad it did not destroy the mold. The Vaseline will make the casting very difficult to paint because paint will not stick to it . It will be very difficult to clean off plaster.
If you use the pink foam Steve referred to in his video you can use wire brushes and wood rasp to shape the foam into the mountain. That is one of the many ways movie sets are made. You will need heat to shape white foam unless you like the way the beads look.
You really need to use pink foam if you can find it. Steve explains why here:
http://gameterrain.info/articles/mattoosup.html
You can create rough strata with the wire brush with a little practice. I like Dagorlad's bark idea as well.
I hope this has helped. Every one has their own ideas. I have found that combining them works best.