A simple jig to hold pin headers in the proper orientation for soldering to a printed circuit board.  I was able to use painters tape to hold this to the underside of a circuit board to ensure the pin headers stayed evenly in place while soldering.

Since exact sizing is critical, I've also included the FreeCAD design file so that users can modify the items in the spreadsheet to change the model parametrically.  I used PLA for this print.