As soon as I can get you to paint my bucket. 
I have not made the flaps yet, but I think the leather is thick enough not to sag into the opening of the tube. I will keep you posted.
I cut the tube with a floor mounted band saw, with at metal cutting blade. I then used a floor mounted 18" disk sander, to smooth the edges and even out the cuts. Lastly, I finished off the edges with a sanding drum on my Dremel. I have access to an industrial metal shop at work.
One of the small perks for working in the auto industry.
Gator