To make sure the glove box door was located as accurately as possible, I put the dash wood into the dash before making the glove box door cut. I then marked the location for the threaded inserts by holding the hinges up against the back of the wood (obviously glove box removed
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On my first "flat panel" version, I made the glove box door cut by placing the original glove box door onto the wood panel and located the threaded insert locations by removing the inserts from the original door, drilling the holes all the way through and using that as the marking template - also used the latch knob hole to mark that location.It ended up pretty close, but the current version is definitely more precise.
Since the contoured dash is too thick to utilize the stock latch knob, I didn't have to worry about it at all. I ended up just putting a metal strike plate on the back of the door and used a kitchen cabinet magnetic latch from Lowe's that installed in place of the stock glove box latch.