There are plenty of boxes available (some of them here), but most are tiny, 1 piece of paper boxes. Sometime I need something bigger, and I bet you do too. This carrier carton is approx. 5-3/4" long, 3-1/2" wide and 3 inches tall, plus headroom. It would fit a couple of muffins or cupcakes nicely. It uses two sheets of paper (print twice). It looks like this:
You can download the template jpg for this box here, and the png here.
Easter is coming, so you might want to grab my "bunny box", if you haven't got it already. You can find it here.here. All my boxes can be found in this folder here.