Very low rpm high torque motor for catapault.?

Hi

I know nothing about motors.

I need a motor I can mount vertically that will give 2-4 rpm, the torque must be high enough to counter the elastic force of some thick surgical tubing. I am looking for the most simple way to achieve this, so no complicated multi unit solutions please.

Im guessing if it was horizontally mounted and the shaft was acting like a winch it would have to be able to lift around 10kg.

I realize that because the tension increases as the elastic stretches that there is some play in the numbers, but an excess of torque wold be preferable to a shortfall.

Anybody know any motors that would work?

PS- Mains current or 12v car battery are both preferred power supplies.