Use at own risk blah blah,

Solder wires to battery, don't use output from charger circuit may kill it (i might have gotten week boards) keep distance of electrodes less then 10mm.

Parts i used;

https://www.aliexpress.com/item/Hot-Sale-1-2-4-8-12pcs-18650-Battery-3-7v-2200mAh-Capacity-Battery-Li-po/32831830258.html?spm=a2g0s.9042311.0.0.T9ZJCf

https://www.aliexpress.com/item/5PCS-Micro-USB-5V-1A-18650-TP4056-Lithium-Battery-Charger-Module-Charging-Board-With-Dual-Functions/32666559864.html?spm=a2g0s.9042311.0.0.T9ZJCf

https://www.aliexpress.com/item/5Pcs-lot-DC-3-7-7-4V-To-1000KV-Boost-Step-Up-Power-Module-High-Voltage/32764213343.html?spm=a2g0s.9042311.0.0.T9ZJCf

https://www.ebay.com.au/itm/Rare-Earth-Strong-Magnet-Disc-Round-Cylinder-Neodymium-N-50-10mm-x-2mm/172863299932?hash=item283f74a15c:m:mpuqcNvkbENux-q06CtDS4w

1.6x25mm nails