With my macs they are in a 950mmLx500Hx500d.
They have a split level so there are 2 of these built into one enclosure with a peice of 5in piping linking the 2 together.
That is heaps of room.
Top has heat bottom has no lights and their water.
I have sand in there at the moment but thinking of changing as the boy keeps getting a mouth full of sand every time he eats.
Als o found 1 log is suffiecent,they do climb a bit.
Just make sure they room to get away from each other if need be.That is why i like the split levels.