tubbing

i have a 77 monte carlo and the back wheelwells in the trunk are in prewtty rough shape, i heard that you can cut up a big steel drum and use that for tubbing, im thinking of doin this instead of patching, plus if i do this i might be able to fit slicks under it

im doin this because its free for everythin except time

anyway how do i go about doin this, how wide do i need to make the tubs

thanks for all the help