[Advil]

There isn't enough of them to make it worthwhile to set up a vacuum pump or get to crazy with fixturing .
And a bit of bow in the middle isn't a big deal tolerances are quite large .
Parts looking good is all he is really after .

I didn't think .030 was going to be quite enough to hold them , more or less was hoping I was wrong about it .
This guy really hooked me up with the first job and I want to do this one as cheaply as possible as a thank you .
I can just go with 5/16 stock easily enough and deal with a few extra minutes run time .

You don't need a crazy fixture, just put a cheap piece of aluminum down as a fixture plate. Drill and tap it to match 4 holes in the corners of your stock. Now set up a quick and dirty repeatable drill and counter bore for your stock (counter bore so you can face the stock with it bolted down) and size them big enough to make 2 or 3 parts at a time. Use tabs on the parts on the last .030 or less. When the first side is done cut them loose from the tabs and deck off the tabs when you face the other side to finish. You should save enough time making 2-3 at once to make the other steps more than worth it. The thinner stock should be no problem like this.

Option B might be to just do the superglue and tape thing. At 4 inches and 1/4" aluminum that should be a pretty ideal type of setup for the tape and glue trick.