I want to build a waterfall for my chameleon tank but unsure how I get the finish i want. I've seen lots of videos on youtube of how to get a perfect glass finish on a resinned object but that is far from what I want, as i want a stoney texture (granite look and feel) as well as tree bark. I've been told I need to make a mold out of polyurethane expanding foam and to resin straight to it meaning that the foam will be permanently attached which is not what i want either, then put a gell coat on top. As I understand it this would make it shiny but waterproof. As i don't want a shiny finish i was wondering if I could mix or put sand on it while it is wet. I would be very grateful for your experience and comments and help with this as i have never used resin before but up for the tasks ahead.