Who doesn't love a meatloaf? (If you eat meat, that is.) Sliced leftover meatloaf is great in sandwiches, and it's also very nice in a bento box. Meatloaves also freeze very well, since they have a moistness to them.
While I do like to make a big meatloaf now and then, I also like to make these mini-sized meatloaves specifically for the bento freezer stash. I often reserve a couple for dinner, and wrap and freeze the rest.
You could use your own favorite meatloaf recipe for this, but here is one in case you need it. The key point here is the size, perfect for bento boxes and sandwiches.