JohnE: Thanks! I didn't want to seem like I was lazy ... it's just that the McMaster-Carr catalog has a ton of stuff. This particular suggestion is very helpful, because I was searching around on the Internet some time ago for large-size rubber bands and just couldn't find a good source.

I am still going to experiment with cutting up bicycle inner tubes ... but mostly because it's in the spirit of this forum i.e. being resourceful.

thanks,
other Pete