Second side complete but with the tabs still attached.
Part bolted to the fixture. I start out with just 3 bolts and machine around them.
Simple fixture for the second side. It's just a piece of scrap with the bolt pattern drilled in it to match the part.
First side complete. The holes are "tabs" for holding the part for the second side. 2 of the holes are reamed for a .250 dowel pin. This ensures the features on the second side are in perfect relation to the features machined on the first side.
Into the mill. The first side can be done in a vice.
The part starts as a 1" thick piece of 4140. Cut to length, and well deburred.