If you gut, skin, debone, decapitate, and fold, you can stew a small squirrel or chipmunk in the Nalgene cups. It just looks kinda funny, and you are constantly adding water so it takes forever. The USGI canteen cup DOES hold about twice as much, and is the best arguement in favor of that canteen.

Mark, if you are looking to repack in mess tins, check Major's Surplus and Sportman's Guide, one or both of them frequently have Euromil surplus mess tins from either France or one of the low countries that is about 7.5x5.5x2.5. Leave out the third, inner piece, and pack your gear into the two shells. It leaves you with a container to hold your kit while you cook, or you can cook two things at once (not the worst idea if you if you have to boil water- the fire is making more heat than the boiling can use). As I said elsewhere, I'm pretty sure my car running over it wouldn't hurt it. VERY similiar, although with a lower end (IMHO) handle is the British mess tin.

Unfortunately, I can't find it at Sportmans Guide, and Major's website is misbehaving right now.

If you are looking for the best bang for your buck, try a Wally World grease pot. They hold about a quart of whatever, weigh almost nothing. The ultralight camping crowd has been very fond of them for a long a time, they weigh maybe 8 ounces and run about five, six bucks. Look around by where they have the tooth picks and measuring cups, it is in a funny spot in the planogram. Keep the inner strainer/steamer tray or not is a personal call. Down side is that there is a small rim along the inside, that either needs to be done away with, or cleaned with a cut down toothbrush, and it has not handle. If you carry a leatherman or similiar, you are fine, otherwise you want to pick up a small pair of pliers to tuck into it and use as a pot grabber.

It's the top item on this page
Very good write up on it

You can see pictures of both here. I use both, but the mess tin is the core items. If I have to shed the rest of the pack, unless I'm about to go into rapids, being chased by an angry mob or something equally immediate in it's lethality, I'm taking three seconds to pull that out.