STL and assocaited files for printing the Glock Rails
Print the non-P80-style front rails front-side down so the layer lines run vertically through the piece when installed. This is for maximum strength.
Print the P80-style front rails however you want. I mocked them up for someone else and have not tested them myself.
Print the rear rails however. Their only purpose is to keep the slide in alignment and see minimal shear force. Front side down would be best, but the pieces are so tiny itd be impossible.