Single to quad 18650 holders with keystone terminals

Not found an 18650 sled that suits my needs.
These are all 20mm wide x 80.55mm long.

Designed for unprotected cells, it is not far off fitting a protected, you could probably print 2-3% larger and it would fit them without upsetting the other dimensions enough to make a difference. 1mm longer would probably do it, so 2%.
The spring on a flat top is compressed to around 3mm deep, a nipple top unprotected should just fit. I have none to test with, I have another 1mm compression available though.

Terminals are keystone electronics "Contact Battery Neg Spring A" and "Contact Battery Positive End A", digikey part numbers 36-628-ND and 36-595-ND

https://www.digikey.com.au/products/en/battery-products/battery-holders-clips-contacts/86?k=628k-nd

https://www.digikey.com.au/products/en/battery-products/battery-holders-clips-contacts/86?k=595k-nd

The "basic" part is intended to have nearly 2mm of terminal poke though the base which can be bent over firmly retaining it, since placing this on metal will cause a short the "insulator" part is optional to fit over the bent terminals, just fits. Melt, tape or glue the parts together.

"pcb" is for pcb mounting, it will slip over the top of termimals soldered to a board, the centre terminal spacing to the middle of the metal on the pcb is 68.54mm according to the design.

Not tried printing the "wired" versions yet but they are intended to allow heavy gauge cables to be soldered to the pins in many different ways then held in place with hot melt.

The keystone_term_plus/minus are not intended for printing but in case you want to model something yourself.

Battery are easily gripped and come out easily enough.

Let me know if you want any easy mods ..