Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4550150.

Replacement pin to hold the support arms to a Rondine Balcony Box. The original mount points are integral to the planter box, so this part is designed to insert into and be retained by the existing hole in the planter. It is also designed to be printed flat on the build plate for strength, hence the pentagonal shape.

This is the specific box: https://www.bamagroup.com/en/rondine-balcony-box-fiorierarondine.html