This is an enclosure designed for a Wondom BCPB2 3S 18650 power supply board, but using a 3S3P battery pack, 3 cells in parallel plugged into each of the 18650 holders, for a total of 9 18650 cells.

It's still a little experimental. I've printed it and it works, but it's a tight fit and there's some room for improvements to the top plate. I've split down the file into sections for easier printing so some assembly is required.

The lower section is designed to be glued together, and the upper section is held on with M4 bolts and nuts.

I don't know if using the board like this is safe or not so do so only at your own risk. I've had mine running for a while now and it hasn't exploded, but I take no responsibility if you get less fireball free results. Please take appropriate care when handling lithium batteries.