As the space between rods of my rail isn't consistent I couldn't use models attached between two ‘easily’ I designed this simple planter using:

• the planter itself
• the collar
• 2 M3 inserts
• 2 M3*16 screws

The planter is designed for 13mm rods + 0,5mm thick soft/sticky layer for adhesion/friction. I used a used latex tube.

The planter is held in place at the top with the collar and a centering bit at the bottom is here in case of bending under weight and/or warmth.

I incorporated an overflow: If there is more than 2cm of water at the bottom of the planter water will drop. For the moment water is dripping on the rail but feel free to add a collector for excess and/or connect several planters.

I printed this in a yellow petg from Poland (Amazon Basic) using a 0,6mm nozzle and 0,35mm layer, 100% infill.

I don't share the .3mf as my mini is tuned (Orbiter 2.5 + Triangle lab TD6 hotend).

As allways the freecad model is provided for easier adaption to your need.