Well here is my first simple basic design lol. True there are a ton of betta cubes, but how many have the sand feature rofl... I was going to make it 3d looking but my tablet isn't hooked up yet.
Try not to laugh.
the bottom will be 100% however you want it, cause it would be your design. Though these may not be exactly correct sized for the tank to slide and fit nicely on the sand, I thought it seemed like a neat idea at the time. It would take up a little more space then the evil AquaBlock and still look nice, you could use a pad style heater for under the tank, as it sits on the sand it would help spread the heat. I dont know maybe I envisioned it to look better then I made it seem.