Some thoughts I've kicked around:
- Build a paper ring. Maybe. Need a stiff mandrel and some suitable thick paper (gummed packing tape or whatever). Building a ring would give me more control over the size. Would there be a significant weight savings?
- Build a ring from 1/64" ply. Still need a mandrel and I'm sure I'd ruin my plywood. Would reduce the weight by a couple of ounces (actually weighed the material).
- Build a ring from fiberglass. Messy and by the time it was stiff enough it would probably be too heavy. I've only built a few 29mm and smaller tubes.
- Build a balsa ring with rib and spar techniques (now I'm just sounding crazy).
- Use the paper mache round box but lighten it up.
PS - A Mini Bertha and a part of a Quaker Oats bin would also work well.