OK, here's my temporary bunny holding solution ... take those nice tyvek feed bags and a roll of duct tape and a bunch of cardboard boxes (cereal cases work well).
Pull the ends of the tyvek bags loose and carefully cut up the side of the bags (I used 4), next, open the cardboard boxes up flat ... it you do it right, you end up with a little flap that is useful when attaching. Now, find a spot in the house and measure out ... my cardboard corral is 4 boxes and will hold 6 growing fryers no problem. Tape the cardboard boxes together side to side, leaving the bottom flaps loose. Once it is connected, place it with the bottom flaps to the inside in the area you will house the bunnies and make sure it will fit. With it in place, lay out the tyvek bags so that there is a 12-18" wall up the inside of the cardboard. Starting with the top edge, tape with duct tape until all the sides are covered. Next, start taping the seams, trying to leave enough slack in the bag to make the transition from vertical to horizontal, but if there is a bit of a slope, don't worry, the bunnies will love it to play on :lol: I also spread an old sheet in the bottom as they will poop and pee everywhere and I just take the sheet up each day and shake it out over a flower bed (pre-fertilizing) LOL
If the babies are small enough, you don't need to tape the top flaps, but when they start jumping, you will want to tape those flaps together also LOL
This is a good way to "peoplize" skittish or standoffish bunnies too! It won't take long before the bunny is standing up looking for you :lol:
When done, pull the bottom flaps out, flatten it all down and fold it for storage until needed again. It is also a great transition for weaning especially if you are selling for the pet market!
Now, if you really want to give them a fun place, cardboard boxes with holes and taped together on top of each other in a bunny condo configuration provide hours of fun and a hidey hole for the younger ones to pile together to sleep. I have found that babies don't generate their own heat until about 6-8 weeks old, so they need a small, enclosed area to pile together for warmth until then.
The cardboard cores that crochet thread comes on make good play toys, especially when you tape 3 together, and then cardboard oatmeal 'cans' make good ones for the larger bunnies. I also stuff hay into toilet paper cores, and then the thread cores to help keep it from being spread all over :lol: