I made 2 more of these yesterday afternoon and I made 3 more of them this morning, so that is the 6 required.
With my method of clamping on to a sacrificial piece of hardwood, there are inaccuracies in thickness of the parts. If I clamp tighter, I get a thicker piece. Most of these pieces are between 9.96mm and 10.02 at the edges and about 9.85 to 9.95 near the middle ( depending which part you measure ), because of the way the piece is bending when clamped. But one part is about 9.88 all over, where I didn't clamp it so hard ( to try to reduce bending ). I could improve this, by using some aluminium to act as the sub-table, but this would make everything more expensive. I think these are meant to be fairly low cost parts. I will try clamping more gently for the facing operation, but adding 0.1mm to the programmed depth.