Hello again Denise ,
So all you really need is something like a potters wheel but better adapted to your purpose and with broader and especially higher speed range . You can actually do all of this just with a modern electric motor and electronic speed control . Mount the motor axis vertical on a solid stand and use large bought pulley as mounting for canvas frame centre .
There are lots of suppliers and lots of ways of doing this so first off have a browse here :
http://www.newton-tesla.com/products/index.htm
These people supply industrial versions of what is needed but there is a lot of good basic explanation on the site .
An alternative cheaper way would be to use an ordinary largish variable speed power drill , one stage of belt and pulley speed reduction and a DIY working spindle .
Simpler still would be a cheap (Clarke) fixed speed motor , belt drive again , but with stepped pulleys to give two or three alternative fixed speeds .
For your larger work it would be best to keep speed to modest levels for safety .
If you are doing this work in a college they may require you to have safety guards . Putting the spinning table in a simple wooden box with only the top surface showing would probably suffice .
MikeW