I often need to buy DC jack for DIY electronics and sometimes I get the wrong type. I made this dummy jack to put in my pocket and always be which me to check if the appliance or power brick is the correct type.

Print settings

I've added big enough tolerances so it's easy to print. If you clean your bed it should print on PEI plate with no brim needed. If your printer knocks it - add brim.

I printed in PLA with 0.4mm nozzle, 0.2mm height, 0.25 for the first layer. You could print in PETG to reduce the chance the pin in the female receptacle brakes. Although it shouldn’t break that easily because it's recessed.

Postprocessing

First you need to remove the support as shown in the second photo.

How i t works

It is a 5.5x2.5 female and 5.5x2.1 male connector in one piece.

If you can plug a DC jack at the female end it is a 5.5x2.5. if you can plug the dummy jack into a receptacle it's 5.5x2.1 type.