After reprinting a PLA template at 6mm thick and sticking it to a new piece of wood, I took it out to the shop to see what would happen. The tl;dr is: SUCCESS.
Initially I started with the 1/2” flush trim bit in the table I was using the other day. I wasn’t having much success with that bit. It keeps rubbing the PLA and degrading the surface, and it had an excessive amount of ‘chatter’ that I wasn’t expecting. I think my collet may have been bottomed out improperly or something. After a few minutes of fighting with it, I switched to my 1/4” collet and the new 1/4” flush trim bits I received from Amazon the other day. These things are high-grade Chineesium. One has a bearing with a ton of wobble. The other, had a pretty decent bearing on it. I checked that both were tightly screwed in before trying the better of the two bits. If the bearing was going to be loose, I was going to lock-tite it back in place. I didn’t need to. After just a few minutes with the router, the template was done. The cheap bit worked better than I expected it to.
From there, I moved to the drill press, with #14 and #40 drills. Using the template still carpet-taped to the piece as a drilling guide, I drilled out all the holes. This worked marvelously.
The rear panel came out quite well.
Despite a huge mess and the template breaking when I removed it from the freshly created piece.
Now the question is, will the 3mm tmplates I printed last week work with the 1/4” flush trim bits?