I cant find commercial cages that are big enough.
*grumble* Commercial cages aren't even big enough for dwarves!
I made one out of 3 ft tall play pens but she jumps out
They actually make 'em up to 48'' tall; an extra foot could make a difference. The two I recommend (based on price and the fact that a door is pretty much a necessity with 48'' tall pens) are
this one on Amazon and
this one on Petco. The prices of both are prone to fluctuating significantly; right now, the Petco pen is definitely the better deal at $57.99 with free shipping.
Another option is a
pen with a top... I've never owned that one but have heard from another RO member that it's *extremely* customizable (ie it doesn't have to be the size/shape it's advertised as). The one drawback is that it's only 24'' high and has a ceiling, so it could potentially be a real pain to access a bunny that was playing "hide and seek" (not to mention, a pain to clean)... however, you could use zipties, carabiners, dowels or 1x1s (for support/shaping, etc.) and other inexpensive things to ghetto-rig the roof to where you can just unclip a couple hooks and lift half of it up/fold it back so that you can get into the pen easily.
Alternatively, since you've already got 36'' pens, you could zip-tie NIC cubes to the top of the pen (and to each other, of course) so that you add another 14'' of height to the pens you already have. Foot for foot, playpen fencing is a lot cheaper than NIC fencing of the same height... but if the "wrong" pens have already been purchased and you need to add some height, it comes out a LOT cheaper than buying new pens.
I think the build your own cube idea is good but I am worried about her weight when she gets older and so it would have to be single layer and I would have liked to get her space above the floor as well.
You're severely underestimating NIC condos' stability and strength - I'd bet my own bunnies' lives on a well-constructed condo being able to handle an adult flemmie with ease
. If you've never had a NIC condo, it's natural to feel like it would surely be too flimsy to feel safe enough for your liking when a 20 lb or something rabbit is romping around on upper levels... but their appearance is misleading! NIC condos are BEASTS once they're finished.
Here's the second one I built (my current one):
Because of the door placement (on the front side, the two middle grids of every row open on every row except the very top), the area just inside the doors is the structural "weak point" (ie the least well-supported). The other week, I wasn't thinking and plopped down a bag of wood pellets weighing 30+ pounds right inside the doorway of the highest level... then did a double-take when I realized what I had done and that the condo hadn't even flinched!
My condo is actually on the "flimsy" side compared to one that's built to maximize stability and weight support. Things you can do differently to make a condo even sturdier:
~ use 4 of the 4'' zipties on each seam between two grids (instead of the normal 2) OR use 2 but use 6'' ties - the extra length is wasted, of course, but 6'' ties have a much higher weight rating (safety-wise, I'd rank them as equal; cost-wise, using extra 4'' ties will come out significantly cheaper)
~ stagger door placement - when planning where to place doors, I went for maximizing ease-of-cleaning and access to bunnies; if the doors aren't all one above another on the same side of the condo, it'll be able to support more weight. For the most stability gain with the least sacrifice in terms of cleaning ease, I would place the condo in a way that neither long side is against a wall (unlike mine) and put the ground floor and third floor doors on the front but the second floor doors on the back (or vice-versa).
~ I use coroplast flooring with dowels for extra support (to prevent the levels from sagging)... while you can add more support by using more dowels, the strongest solution by FAR is to use plywood instead of coroplast. I recommend something in the 3/8-1/2'' (nominal) thickness range - thick enough to be very supportive without being so thick that you have to worry about how much extra weight the plywood is putting on the condo frame.
[As a note, you need to use untreated hardwood plywood - soft woods are toxic if the bunny chews or pees on them (unless kiln dried, but KD pine plywood is really rare), plus they're bendier so they add less a lot less support. Treated wood is toxic and MDF, OSB and particle board are no-nos because of all the glue involved, plus OSB would be a splinter hazard.]
Using plywood is the biggest stability upgrade by far... the downside, of course, is that it's not waterproof. However, that can be remedied by using it as a sub-floor with something that *is* waterproof on top of it (coroplast, vinyl or laminate flooring, etc.).
~ If you need to make a "step" between two levels because they're too far apart for the rabbit to just jump up, make sure it goes all the way across (like in the picture of my first condo below) rather than just being a single grid attached to a corner like in my second condo.
[Note: never make the ground level only one grid high! It's my biggest regret by FAR with that condo because it makes cleaning a real b*tch. I did it that way because there's no interior access between the first and second floors - instead, they jump directly into the second floor from the attached run. With the second condo, I can sweep it out without getting down on my hands and knees.]
~ Also, do NOT rush to judgment on the condo's stability until it's done! I remember when I started making my first condo, it felt so flimsy/wobbly and I was *really* worried that there was no way I was going to be able to build the 2x3x5 size condo I had in mind and have it come out sturdy enough for me to be comfortable trusting it with my bunnies. Finished, it can handle me really putting my weight/strength into pushing on the longer side to coerce it into sliding across the floor.
In other words, what looks like a lost cause to a novice NIC architect in the early stages of building ends up being more than sturdy enough to meet even the most paranoid bunny parent's high standards once it's finished
.
~ I've never owned a giant breed, but I'm guessing they move around and such a bit differently than a teeny dwarf, so some non-stability-related accommodations may need to be made (relative to my designs, which were built for dwarves) to make it easy and comfortable for them to get around in the condo.
(I have a 3.75 lb lionhead, 4.5 lb Holland and I'm working on adding a 5.5ish lb sable mix that I adopted last December (ie bonding them into a trio so they can safely live together)).
~~~~~
Some helpful NIC condo related links/info:
These two sites lay out the basics very clearly:
http://breyfamily.net/bunnycage.html
http://www.guineapigcages.com/cubes.htm (shows how to do coroplast floors if you'd rather use that than plywood)
And this site that JBun found gets into the nitty-gritty details - lots of different designs, some in-depth videos, all that good stuff:
http://rabbitcondo.com/lara-and-harrels-deluxe-wide-rabbit-condo
The best deal on grids for the cages (in the US) is - surprisingly - at
Sears (if your local store doesn't stock them, you can do site-to-store to avoid shipping fees).
How many boxes you need obviously depends on the design, but you'll need at *least* two boxes to build an appropriately roomy condo unless the bunny is 100% free range and only uses their cage/condo as a home base for their food and litter box. Each box contains 23 grids.