One of my folding camping chair broke at the base on one of the corners. This chair model has joining square pieces at the base that are 52-53mm wide and long.
...Plus Searching Thingiverse I found a STL file for a smaller type of folding chair. I decided to design a new CAD file using Fusion 360. It's made for 17mm diameter tubes. 4 identical pieces are used at the base of the chair.
