How much space he needs depends on whether he's free-range or not. Non free-range bunnies need either 60 square feet of space (generally accomplished by setting up playpens around a NIC condo) or 4-5h outside the cage to roam around each day. If he's free-range or has a permanent "run" set up around his cage, then size doesn't really matter. If he's going to spend a fair amount of time in just the cage, then bigger is always better (especially since rabbits have weird sleeping schedules and are often awake/looking for something to do in the middle of the night). I recommend a minimum size of 4 grids long x 2 wide x 2 tall with two levels for a rabbit that spends a lot of time in the cage. You can just barely accomplish that size with two boxes of grids that come 23 to a box. My bunnies (lionhead and holland) have a 4 long x 5 tall x 2 wide condo (three levels - the first and third are two grids high/the middle is one grid high), which took about 4.5 boxes... but then, they're extremely spoiled
. Back in San Antonio (I'm currently living in Houston with my boyfriend while he finishes school), they've got a 2 wide x 3 long x 5 high three-level condo:
(Sorry the pics are so small - too tired and lazy to resize them through Photobucket and the normal versions are obscenely huge so I went with the thumbnails.)
In both locations, they live in a pen because they can't be trusted to free-range. I tried it here, where the floor plan is less open and bunny-proofing was easier, but they bullied the cats incessantly, peed all over ALL of the cats' things (including some bunny-friendly "cat" furniture they were supposed to share), ate cat food at every opportunity and camped out in the cats' litter box as though they were claiming it (I use the same pine pellets for the cats that I do for the bunnies, since clay and/or clumping cat litters are extremely dangerous for bunnies)... so they lost their roaming privileges. The poor cats were so grateful when they were no longer being driven out of the living room by naughty little bunns!
I use coroplast for my cage flooring - it's corrugated plastic, so similar to cardboard but more durable and - more importantly - waterproof. Keep in mind that litter box training is almost always *very* hit-and-miss in very young bunnies... and more often than not, males start "spraying" urine when their hormones kick in, which can only be stopped by getting them neutered. That was my original reason for using a pen instead of free-ranging (I got my girls right after they were weaned).
The best deal I've found for coroplast is at Home Depot, assuming they carry the 3' x 6' sheets (I think they're about $14). If you go there to buy it, don't ask an employee where you can find the coroplast - nine times out of ten, they won't even know what you're talking about. Ask them where the *plexiglass* is, since coroplast is always in the same spot. As a note, a 3' x 6' sheet can be gently/loosely rolled up and stuffed into the backseat of a car, so unless you drive a tiny sports car with no back seat at all, you should be able to bring an uncut sheet home
.
The only tool you need to work with coroplast is a cheap pair of box cutters or an x-acto knife or something. Instructions for making coroplast floors for NIC cages can be found
here.
As a word of warning, you might want to use *just* a playpen for the first week to be safe. I suspect it wouldn't be an issue with a 9 week old Holland because of their wider heads and the fact that their ears don't pop up, but when I first tried a NIC enclosure, my 9 week old lionhead got her head stuck in a grid. I had thought her head wouldn't fit, but she proved me wrong. It was a terrifying experience for us both... I kept her calm and still so she wouldn't hurt herself and tried to free her to no avail. Finally, I cut the zip-ties around the grid she was stuck in and rang my neighbor's doorbell at 7:15 in the morning, while holding a bunny with a grid around her head, and asked if they had any wire cutters I could use. The wire cutters didn't work, but she was able to look at Nala head-on (which I hadn't been able to do because I was on the butt-side of the grid to hold her) and commented "you know, I think it's just the ears stopping her from getting free." Lo and behold, I tucked her ears back through the grid and her head popped right out. Gazzles (my Holland) was 10 weeks old at the time and her head was already too big to fit through.
Best deal I've seen on grids for the cages is at
Sears (23 grids to a box) - if your Sears doesn't carry them, you can get free site-to-store shipping (shipping to home is prohibitively expensive).
Shameless self-promotion moment... I actually sell 4'' zip-ties on
my website (which is for sugar gliders but has a little bit of bunny stuff) - they're about halfway down the page. It's something like $17-18 iirc for 1,000 cable ties at Home Depot (and the 100 tie bags are like $5!); I charge $3.80-$4.05 (black costs more than natural for some reason) for 500 (which should be enough for a NIC cage). As a note, my selection of glider stuff is way too broad to be able to set up truly accurate shipping fees in PayPal - it ends up over-estimates shipping fees most of the time (especially with very small orders), but I *always* refund the over-charge when the order ships so that people only pay the actual cost. If all you ordered was 500 zip-ties, PayPal would charge you $4.09 shipping but you'd end up getting a $2+ refund.
For a basic pen, the best deal I've found is
this one (normally $35 for the 25'' high pen; free shipping and it's Prime eligible); the 30'' high version is $40. If you want something taller than 30'' (like if your bunny's a jumper or you want to be able to put cardboard boxes and such in the pen without worrying that they'll be used to jump out of the pen), I recommend
this pen... which is apparently silver now, the jerks - when I bought it, they only offered it in gold and I'd much rather have gotten silver. A 4' tall pen is $58 with free shipping.
You can zip-tie the ends of the pen to the sides of a NIC condo, or you can zip-tie them to the wall by putting 2-3 screw eyes in the wall where you want to connect it and zip-tying them to the screw eyes (which is what I've done at the apartment here in Houston). Both playpens I linked are 16' long - if you attach the pen ends 8' down the walls from a corner, you end up with an 8' x 8' enclosure which is 64 square feet and meets/exceeds the 60 square foot minimum that a bunny (or pair) needs if they live in their enclosure full-time. The screw eyes will run you about $3 total - much cheaper than buying a second pen!