Is it possible to make DIY rock without using the "tote full of sand" / molding technique? I can't figure out for the absolute life of me how that works, and I want to make a double arch-type shape in the future for a bigger tank (think: like a flat 'm' shape) but the GARF technique is hollow (which I don't want) and uses the sand technique (which I can't figure out). Is there ways of putting it on / in other things to make convincing looking rock that isn't a million pounds and made in a sand filled bucket? Maybe 'sculpting' it? Using a different type of mold? Covering something else with the aragocrete mix like PVC pipes or something?