I've never steam bent anything, and now I need to steam bend some 16" perfection shingles, all VG.

I don't need to do many, maybe 16' worth of a single course, and it's not going to be much of a curve.

I ordered a wallpaper steamer, and my plan is to get an 8' section of 18" diameter sono tube, stick all the shingles in there (after soaking in water for 10 minutes) and start steamin!

I think I have it all figured out except how to seal the ends of the 18" cylinder while it's steaming. I could cut two 18" circles out of plywood and use those, but was wondering if someone had a better idea of how to seal the ends??