EDIT 1: After printing (About 5hrs) I noticed I made a mistake in the holes for the step down converter, which is this OSKJ:
The holes for the screws are totally off, and also the little tab for the switch is too small to allow the heatsinks and switch to be mounted together, but i don't mind, it's working, slow charging my savaged batteries..
EDIT 2: Added V4 File. I redesigned the thing, now it fits perfectly the step down converter and saves a bit of material, I also realized i dont need the two charging boards, since i can adjust the constant current and constant voltage with this step down converter, so i can conect it direct to the batteries respecting its charging currents limitation, using a safe (i think) current value of:
( BatCapacity 0.4) NumberOfBateries
And voltage set to 4.15V
Be careful with this setup, overcharging or overcurrent your batteries may cause severe damage!
Always pay attention if the batteries arent getting hot! its a bad sign, normal bateries don't get hot while charging properly.
I'm too impacient to charge 4 batteries at a time, and i had some cool stuff laying around, like a Step-Down converter, a Notebook charger, and a switch, so I made this to charge up to 8 Batteries using two chinese modules, the step down and the notebook charger. Nice and useful. May explode, so be careful haha
3D Prime PLA