Turns out, I’ve managed to get some grids! Roberta (the saint!!) managed to find some online, at a fair price and within Australia, so I’ve ordered some to get Apollo a bigger cage! And I thought it wasn’t possible!
The parents (BOTH, DAD INCLUDED!!) have agreed, and dads even promised he’ll help me put it together, make shelves etc!
Ive ordered enough to make a 3x2x3 (3 grids wide, by 2 grid deep, by 3 grids high.) Apollo is a mini lop, he’s 4 pounds. I think a condo this size will be okay for now, but, with the beauty of them, I can always expand later. 
My questions to you guys is, how should I plan my shelves to maximise space? I’ve measures the size of the nic base compared to his current cage base, and they’re the same. This means that I can use his pet store base for the base of the condo. But I’m stuck with shelves. What materials do I use? What size do I make them for the condo plan?
General help needed for a first time condo builder!
– Thanks everyone!