I did quite a few with aragonite sand, crushed oyster shell, rock salt, and white Portland cement. Using damp sand bed to create a mold, you can use chunky rock salt to create cave/little hole for critters. When you make a shelf rock, remember to get frag plug and imprint it shape to the rock or simple just make some hole so you have place for frags that your doesn't look like a frag tank.
They are not hard to make, I still have almost everything to start, I'll give it to you if you want to try. The hardest part are waiting for it to cure, it'll take months before you can start to cycle them.