Originally Posted by Italy592
Well I was always planning on doing the cement but I was wondering if people use something else or not
I wouldn't know what else to use, on polystyrene. You could use fiberglass but you'need something other thank polystyrene because I'm pretty sure that epoxy will melt it. You also won't get that grainy "rock look" with fiberglass.
Here's what I got with SANDED GROUT. I applied it using my hands (with gloves). It has a nice "sand stone" like texture to it