My first tooling plate was this one. I made it partially by hand and part by CNC. The CNC router that I made is posted here:
It was well tested making model airplane parts and I wanted to see what I could do with aluminum.
The holes were all placed using a 1/8 drill bit and the CNC Router. The groove around the periphery of the plate was cut with a 1/8 carbide end mill. The outside perimeter of the plate was edge milled with a 3/8 end mill for the full height. (1/2" high). The holes were then drilled and or counter bored as needed. The CNC saved a lot of time by eliminating all layout work (of course I used a lot of time with CAD and CAM but it is all part of the learning process). The 1/8 groove can be used with a thin parallel for quick work alignment. The 1/8 holes were drilled out to threading diameter on the drill press which was quite fast. All of the threaded holes are 1/4-20 that were manually tapped. Sort of manually tapped. I used an air impact wrench and a tap holder along with my drill/tap guide block and tapped them all quite rapidly compared to complete manual hand tapping.
Bolts to the mini mill and covers the entire table. The counter bored holes are for bolting to the mill table.