I needed replacement caps for my old ladder and the best I could find was larger one with two holes. I needed the smaller set. I remixed with Tinkercad to make the smaller cap with one hole to match my ladder.

Assembly: The original caps were aluminum riveted. I drilled them out with a ¼" drill bit. I bolted the new ones on with ¼-20 stainless steel screws, washers, and nuts. 

I made these about two years ago with PETG for the durability. Not sure of infill, probably 50%, 0.2 layer.