I made a quick model in TinkerCad and it actually worked first try, this is the perfect size for the two folding tables I tried it on as it holds firmly but is still removable.
 

Purpose:
This is a clip designed to attach to a wall and hold a folding table steady. 

Specs:
The clip size is 25mm so check the diameter of your table leg to match.
The clip is 35mm from the wall check the distance from the leg to the wall to match.
The clip is 30mm width and 30mm tall, adjust this if you change the clip size.

My Settings:
The picture of Cura shows the method for getting the infill to show, namely making the top and bottom layer 0. 
All my other settings are basically stock Ender 3 settings, and the filament is Esun PLA+