Putting a T-slot in a curved edge.

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If you're rolling it you can put a piece of strip inside the slot to stop it from collapsing and slide it out. The mental picture makes it a bit clearer, the RAF had a reversed tee slot on the curved slides that held the polaroid visors on the early bonedomes. Regards Ian.

The other way is like the adjustable angle drilling tables with the curved bases, similar in cross section to cedge's latest engine.