I use zip ties to hinge the doors. If you don’t tighten them all the way and leave just a bit of slack, it is enough to open and close them. The NIC cubes are a LOT of fun to make…enjoy!

The NIC cubes are so much fun to design.  I have a 4 story and a 3 story house.  They are under the "Cool Habitats".  I also use the electric ties.  Once you start putting it together, it is so much easier to understand what everyone is talking about. 

You make the floors using the wire panels, and then place something over the wire for the buns to walk on.  I use plywood for my floors, but others have used cardboard, coroplast and rugs.  To make two levels, you basically use a cube with no bottom for the first floor, then add another cube with no bottom on top of it for the second floor.  It is actually easier to do than to explain.  When I first tried to build ours none of this made an sense, but if you just lay out the panels, and try different ways of stacking them you’ll get the picture right away.  I’ll second the zip/cable/wire ties idea.  I tried using the panel connectors, but they popped out way too easily.  I just ditched them and went with the zip ties.

The panel connectors I found provided stability for the panels, as for the door hinge, I used zippy ties, but you can also use small notebook rings too. I use a scissor snap hook to lock the door. Flooring I used the wire panels and I wanted something more solid so I used some pressed-board and stuck vinyl tile on top. Then my final layer of granite tile, or another board with carpet attached with carpet tape. This way I can lift out the tile & carpet for cleaning while still having a surface that is easy to clean and safe for the bunnies while I clean the tile and/or carpet. Sometimes a small piece of the connector can get in the way and I used a small craft saw to notch it out for the flooring and/or doors. I would recommend you set up a big space and a bag of 500 zippy ties (no joke) and play around with it. If you do go 3 or more squares wide or deep, be aware that you either need to support the middle panel with a vertical one or I know others have used a pice of dowel or wood to support the upper floors. as for getting to the upper floors, I made ramps and now for variety have made "steps" about 5 1/2 inches high for them. Be diligent when you finally decide and give your bun supervised play time in the new condo then after a few days, take away the old cage once everything is OK and no tweeking is necessary as you do not want your bunny to get hurt.