I used PVC pipes in my apisto tanks, created multi story flats for them, I bought the pipes from my local hardware shop or you could go to a B&Q, then I bought some aquarium sealant, washed all the pipes real well and then cut them to the depth I wanted and glued sections at a time together. Left it for a couple of days for the sealant to go off, to keep the pipes from floating I glued them to a piece of slate that I had bought at my local lfs (after I washed it and made sure that there was no dirt or lose bits still on it).
There you have it a pipe flatlet for all the apisto's to rest sleep and play in.