Belkin Boostcharge Tertial mount

Arm: Ikea Tertial work lamp.  Remove the lamp housing.    

Charger: Belkin magsafe charger model WIA004ttBK.

Hardware:  2x M3 screws, 2x M3 nuts.

Print standing upright to keep inner surface as smooth as possible.  I recommend printing with organic supports, paint on to surfaces, set to 45 degrees.  If you're using automatic supports, put blockers in the cutouts for the nuts since those are easy bridges that shouldn't need support.

Post processing:  Best to do some light sanding and even ran a deburring tool to help smooth the inner part of the ring near the top.  The rubber surface of the magsafe can be scarred by any rough bits.  It's a very snug fit to hold as tight as possible.  

Assembly: The screw holes are reasonably long with the nut cutouts very close so you can use either long or short M3 screws (I've got a lot of longer ones with no other usage).