Have you considered making these on a "modular" design basis? I use a common post that is interchangeable for 3", 6" and 8" top. I prefer round vs. using angle.
Yes it's modular. Post is 1" diameter with top part of the post threaded. Top is a rectangular bar 1.3 thick with a threaded hole at the bottom. Top is vertical steel bar (not angled like on some tool rests)that you just screwed on post.
Horizontal corner(of the top part of tool rest) that is facing turner will be rounded.
About shape of the rest tool... I've read a book on wood turning (can't remember the title) and the author had a very strong opinion that the best shape is a straight bar of steel with top corner facing turner rounded.
He explained that since the highest point on tool rest(it's fulcrum on which chisel is rocking) is very close to workpiece you have bigger leverage, better tool control, less vibration etc.
With round bar style top you move fulcrum point away from your workpiece by half of diameter of your tool rest top.
Since I don't have much turning experience I'd like to hear your opinions.
I would appreciate any advise.
Thanks,
Alex