DIY staghorn rock?

[jgoldsney]

Another method that you could possibly try would be to make a flexible silicone mold.

I used to do this when I played with making my own indoor climbing wall.
I never tried it with cement though (used bondo)

What you do is make a model of what you want out of plasticene or playdoh, then get some silicone and make a number of thin coats allowing each one to dry. after a few coats you should have a flexible mold that you can peel off.

The downside would be that unless you made a bunch of molds your rocks may get boring

Joel