By the by, This has been an interesting thread to me. I have tried many things and there are some good ideas here. Long ago I was hiking with my friend Neal Lind and he was using a 16 ounce plastic measuring cup for his dinner bowl, tea cup and other general purposes. I recently switched back to that. You can always find something to stuff into it so it doesn't take up any volume to speak off. 2.5 ounces?