Decking Installation Jig
Also known as the "Deck d--k" on Reddit.
This is a quick jig that makes putting deck boards on a deck go a lot quicker. It sets the proper gap between the deck boards, and it aligns with the joist beneath and acts as a screw guide so you can quickly and consistently put in deck screws.
The uploaded STL file spaces the deck boards 1/8" apart, and assumes a 5/4 x 6" deck board (1" thick, 5.5" wide). The screw holes are spaced 3" apart, or 1.25" away from the edges of the board. When I'm finished building my own deck, I'll upload some more STL files with other dimensions.
The prototype shown here was printed in PLA, which will hold up if you're careful with it. I highly recommend printing in PETG or ABS for durability if you can.