I find that the PETG does have some shrinkage and most of the holes for screws I make bigger than 3mm in the STL file to accommodate. The pin holes I did not change from the original design size. I thought it would be safer to let them be on the small side so that people can make the hole bigger if they need to. You can also use heat to get the pins in similar to the brass inserts. You might need to counter sink, or chamfer the edge of the hole a little bit in case the plastic volcanos up when you insert the hot pin. Just an idea if its easier than getting a 3mm drill bit.