I made a tractor for mine, and will be making a couple more. In a perfect world I'd like a run too, but I could make the tractors more secure, and move them to fresh grass - it is insane how much pasture a bunny can eat in a day!
I used leftover lumber fencing lumber and made it 3X12. For the sides I used leftover hardware cloth, and for the top and bottom I used leftover 2X4 fencing wire. All I purchased was a bit of plywood for tops and to make a windbreak on each long side. It is VERY heavy, but it also secure.
Things I like:
The security, bunnies have been in it since July - 0 escapes.
The hardware cloth (better at protecting them from my dogs, and also then from other animals).
The 2x4 wire has worked great for the floor, it's big enough they can eat the grass and even dig, but even the smaller bunnies haven't managed to dig enough to go through.
Things I'd do differently.
Next time for the top, I'll use PVC roofing panels, and hinge them to the top(?) still figuring that out.
I'll also make a 2nd level, or possibly 2 of them, one on each side. The buns in this one have wood boxes, an old carrier, and so on, but I'd like to have a floor up off the ground.
I want wheels on the next, or else I need to make the frame lighter. I'm worried PVC isn't strong enough, but I'm thinking 2X2 wood would be fine.
I've had 4 does in this, and it would be great for a litter for growing out. None of these does are reproducing (they're pets), so no idea on that. I'm planning to have it so that all my babies go in these, and also at least rotate my adults into them. The bunnies love it! If you scroll down through my blathering on this blog post there are a couple pictures of it..
http://www.threadtwist.blogspot.com/201 ... oject.html