How do you practice cello without a cello?

you can actually use your right forearm as the 'neck' of the of the cello for your left hand practice. Bowing is harder, but as long as you have good technique its ok. what ever you do, keep relaxed. I've actually bowed a bit in cl with a pen or something. The key is as long as you are 'hearing' the piece in your head as you are bowing or .