I have a tannery 80% AR receiver and a bushmaster 100% AR. I am wondering if anyone has tried to make a template for drilling the safty and trigger holes out of clear plastic or paper and just tranfering from the bushmaster 100% to the 80% casting and drilling or just centerpunching to find the holes?
The  purchase of a jig for one or two time use and the high cost leads me to find another less costly route to the drilling highway!
Has this been tried by anyone?
This is one technique I have used to build some of my AK-47 receivers with great success.

I believe transfer punches have been used successfully for what you're trying to do.  
Some of the holes can not be done this way though.  The buffer extension and the bolt hold open detent come to mind.  I guess all of the detents would be impossible to do.