Clips for Tools modular desktop stand (Tweezer;Plier;Screwdriver) V 2.0

I was experimenting designing and creating customizations for ICT Avatar's 
Tools modular desktop stand. I had printed a dozens or so pieces of the 20 and 40 mm frame modules. I was varying these along with various top and bottom inserts as I created them. I'd typically have a set of 3 -5 frame modules which I shuffled the pieces between. At the time I was using a large rubber band to hold the modules together as a unit. The modules fit together wonderfully well, but they don't snap together. So, it was a rubber band or glue.

I decided I needed a better mechanism than a rubber band, yet one which would allow me the the ability to disassemble and reassemble as often as I wished. 

This project is the result; clips which nestle along the module and hook the ends, all without any modification to the existing modules

Clip Sizing
Model filenames describe which combination of 20mm and 40mm the clip fits. An flat endpiece (p20a.stl) is assumed to be included.

For example, 
the model named:     clip_3x-20mm_2x-40mm. 3mf
fits a combination of 3 20 mm modules (3x-20mm) and 2 40 mm modules (2x-40mm)

Printing:
PTEG or PLA Pro - I printed mine with PLA Pro
0.10 to 0.20 layer height 
Infill: 20%  - it needs to flex in order to attach.
Supports - recommended- add custom support modifiers for the end hooks.