This design is based on Adafruit's orginal jig: https://learn.adafruit.com/heat-set-rig
I had some 3030 aluprofile pieces at home so at first I decided to fit the original design. Later on I have:
BOM:
Feel free to alter the design: http://penoff.hu/Fusion360/heat%20set%20insert%20installation%20stand%20v44.f3d
All the parts are designed to print without supports. The top "cap.stl" is the only one which requires some bridging but I think it is still manageable without adding support structures.
I have uploaded the Fusion 360 CAD file.
The author remixed this model.