This can all be printed without any supports. It's designed to hold 6 18650 cells in a 12 volt configuration while allowing the use of a BMS and battery removal. I've been charging and discharging mine at ~2 amps without any problems. To make the connections around the tabs I used threaded copper wire and stripped about 3 inches which I wrapped around the connection points tied off and glued.
I have been using several of these as USB power supplies, and one powers a raspberry pi handheld I designed. They have all been working great for several years.
Disclaimers:
Know what you're doing, 18650 cells can be dangerous and I am not responsible for any accidents.
This is Not designed for High Current applications. Batteries can get hot when charged/discharged too quickly and this thing is plastic. There are also a lot of connections and any bad connection will generate heat.
Don't short your batteries. Many of these connections are semi-exposed.
Make sure your batteries are balanced and inserted correctly.
The author marked this model as their own original creation.