Always start with the legal stuff

As with all the other parts kits I've built, this CETME kit was once a select fire rifle.  Because of that, the first thing I'm going to do is mod the fire control group so that it will only function as a semi-auto.  The CETME fire control system is similar to, but completely different from the G3 trigger pack so no individual parts interchange.  The CETME is so close to it's G3 cousin that a whole genuine PSG-1 grip assembly would fit on this build with no fuss, but just the grip/fire control assembly alone is literally 8x the cost of the CETME parts kit.  Semi-auto G3 parts are available, but no such luck with the CETME so the original parts need to be modified.  There are several guides available on the internet, so I won't bother going through every step.  

On G3 style rifles, leaving the front grip housing pin in place makes your receiver qualify as a machine gun, so it can't used.  Conveniently, the real PSG-1 lower doesn't use the front pin either so I would have eliminated it anyway.  The first thing I did was whack the ears off the grip housing.

Then I took the whole thing apart and modified the internal parts.  Most of the pieces needed a little bit trimmed off, and the fire control cage needed a corner cut off and a shelf welded in it's place.  Here are the bits after being modified:

While I was at it, I crushed the auto-sear in my vice.  Here's what's left of the auto-sear along with all the other naughty bits that got cut off:

With all the parts trimmed, the trigger pack can go back together.  The selector is still a 3 position selector, but it now goes Semi-Safe-Semi.  Once I know everything works, I'll cold blue all the parts.