Jack Cắm Barrel 2.1mm x 5.5mm

DIY barrel connector for that one time when you need it right now.

Outside barrel is Ø5.5mm so you take M6 hex nut and drill Ø5.5mm hole knocking the thread. 
For inside pin use Ø2mm nail, head sanded into a ball end and trimmed to size.

Ring can be glued on its tab for the thing that you are powering, the plug can still be unscrewed. Printed with fuzzy skin for extra texture for gluing.

Size of the connector passthrough is 3x3mm.

Print the cover with fuzzy skin for extra friction (point distance 0.2mm, thickness 0.15mm).

Tested in PCTG, print file provided is for Prusament PETG.
(For less elastic materials the pin and cover tolerances may be adjusted.)

(Pictures are from prototype universal cheap ringlight project.)

Disclaimer: 
Not responsible for anything bad happening from this janky connector.
Order proper one right now, this should be okay for the time in between.