Compact 5Ah Makita 18V Battery, 90Amps, BL1820 Size, 21700's, High Amperage, High Heat tolerate, HT-PLA-GF

Update: 6/3/2026
I have been annealing pieces, packed in play sand at 100C for 1hr, No problem with shrinkage or warping, the BMS mount piece slightly bends. But flexes back when put in place, I think just packing tighter in the sand could also prevent this.

Update: 5/30/2026
Improved deign, lower tolerances, cleaner fit, So all previous stll files are deleted and replaced (except the button)

This is a 5Ah 21700 battery the is the same size as a BL1820 just 100gm heavier. This will fit in every 18V Makita tool ever created and also any other brand power tool via adapter.
This was specifically engineered to be drop in ready for the upcoming cells: Molicel P60S, M65A, Reliance RS60, TenPower 60XG, etc. 6Ah 21700's up to 100A discharge rates, up to 21.6mm Diameter will fit.
I use large surface areas of solid copper .2 (will use .4mm copper for higher amp cells), thermal conductive tape and grease, etc.

Items for this build:
5Ah cells; I used Reliance INR-21700 RS50 70A, Tenpower INR-21700 50XG 90A (140A pulse) (75C and 80C cut off)
and Molicel INR-2700 42A 4.2Ah 45Amps
.2-.3mm thermal tape 20-30mm wide
5mmx10mm x .5 thermal pads
thermal grease
Fish Tape (vulcanized fiber paper) 100mm wide
.2mm copper 100mm wide
90A BEPA (TPU/TPE should also work) for flexible spacer between the case and top
Polymaker HT-PLA White for button, and BMS mount
HT-PLA-GF Makita Teal for the case
Spring .8x8x15mm
M3 self threading 5-8mm long
22AWG wire 7cm
stainless steel 16-18” metal bands / zip ties
The good banding tool (dial up max tension on the banding tool) (screws always fail with FDM I am over trying to use them)
White spray paint for the metal bands

Generic Makita BMS Charging PCB
https://www.aliexpress.us/item/3256808381364408.html?spm=a2g0o.order_list.order_list_main.11.21ef1802kpOmdD&gatewayAdapt=glo2usa

4015N Digital Voltage display (The battery meter can be soldered on to PCB first then fed through the battery case)
https://www.aliexpress.us/item/3256810228903340.html?spm=a2g0o.cart.0.0.235338dax0yUY6&mp=1&pdp_npi=6%40dis%21USD%21USD%202.79%21USD%202.61%21%21USD%202.56%21%21%21%402101d6fe17792280426084355e32a4%2112000052331936910%21ct%21US%21162043050%21%2110%210%21&gatewayAdapt=glo2usa&_randl_shipto=US

RTV Clear waterproof for voltage display

I use a fiber laser to cut the copper, fish tape, and mark the batteries.
I typed the text for marking, (no vector files)
Fonts used: La Femme Makita, Dune Rising, and Tamil font
When I get a chance I will try to put together a better tutorial. (it just takes so much time)