Just a thought, you could go to a lot of trouble getting that "right", whatever "right" means. But you specify the material as aluminum without calling for any particular alloy. I would try to make one pattern and use a router with a carbide cutter and ball bearing guide to make the basic profile. There is a 1/4" hole that could be drilled in the blanks and used to bolt it down to the pattern. This pattern would be set about 1/2" to 3/4" below a cutout in a surrounding table area for the router base to ride on to leave clearance for the hold down bolt. The pattern could be aluminum while the platform it is mounted in could be wood or particle board. Then the router could make fast work of cutting it with no chance of going too deep. The two inside corners could then be cut on a mill with a bunch of them stacked with the square ends pointing up. This would be far faster than trying to do that profile in a manual mill. Find an aluminum alloy that cuts well with a high speed router bit.
Make it fit.
You can't win and there is a penalty for trying!