Dual battery holder

These are battery holders with magnets so you don't need any screw.

It works better (stronger magnetic effect) on unprotected batteries because magnet is applied directly to the metal instead of the protection pcb.

CAUTION: LITHIUM ION BATTERIES ARE DANGEROUS, YOU HAVE TO WIRE THEM CAREFULLY AND CORRECTLY. IF YOU DON'T KNOW HOW TO WIRE THEM

You can wire them in parallel or serial. On the photo they are wired in 2S configuration like on the drawing. You can also add balancing wiring if you wish

It comes in different sizes: 18650, 26650, 32650. Just print 2 parts for top and bottom.

Bill Of Materials
Links below are affiliate links : it doesn't cost you anything but gives me few cents if you buy something.

Magnet https://www.banggood.com/50pcs-N50-D-103mm-Strong-Ring-Magnet-3mm-Countersunk-Hole-p-940059.html?p=IH111511352354201706
These magnets are quite fragile so handle them with care
Bolt
Nuts (https://www.banggood.com/fr/Suleve-M3SP1-50Pcs-M3-Stainless-Steel-Phi