George,

You could put it back in the NC mill and pocket these out.
Simple set up. Only one set up. The hole NC program could be
the same for all and merely stepped around for each of the
ten holes. Same goes for the four pockets in the center plate.
Should save almost two pounds.

BTW please ask the machine shop people what PC programs they
are using to generate the NC G code. I might be able to
do it on this end for them. Also what kind of machine
is that as each machine manufacturer uses a sub set
of NC G codes?

The reason wall thickness is so important is
going from 5 mm wall down to 4 mm wall will save
20%. 20% of 13 pounds is 2.6 pounds.

It should also be easy to modify the pattern and cast in these
pockets and holes.

The 3D illustration shown  here is not accurate in the sense of 
the raised center section. It is really located behind the front face
and not in front as shown here as you well know. 
Nor is it completely to scale.

Paul Lamar
 
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