Good to hear you are not at a stop with the circles Ross.

I found one of my wife's glass circle cutters.


Of course the center pivot point is a suction cup, but the body parts are aluminum and the pivots are brass bushings,
Scribe lock is very solid when set. I could get a near exact radius by using the built in scale, swing out a circle, and measure to determine the error. I then could clamp a small stop block on the arm against the cutter head, then released the cutter head and inserted a feeler gauge between the stop block and cutter head. Slide it up tight, and locked it down. Worked great!

Now of course the cutters were not sharp enough to slice, just indent.


This is dyed maple:

The cutter head, at the working end, has a nice flat side and locking screw that could easily be adapted to a proper cutter wheel. but the pivot point would need to be changed to something that would work for veneer. 
It's pretty stable, just not quite sharp enough to cut veneer.

Anyhoo, was worth checking out!