Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4151037.
I have an old Dyson DC35 and the battery was dying. Looked online and you can buy a replacement battery pretty cheap from the usual suspects. I decided that I wanted to go ridiculous and make my own using the original board in my existing battery.
This battery uses 12x 18650 batteries in a 6S 2P configuration, I used LG HG2 batteries for the high current (I probably could have gotten more capacity out of lower current batteries due to the 2P design but these are what I had on hand), all of the original electronics, and a 5s battery tester which I got from ebay.
Additional hardware includes 3x M3 threaded inserts, and 3x M3 x 20~25mm bolts.
Support material is only required on the overhang on the top part of the neck, and on the shoulder at the front of the side pieces. everything else can be bridged
I may remake this with thicker walls, but for now it seems to be holding up fine.
If you aren't familiar with working with lithium batteries please don't make this. Lithium batteries can leak harmful chemicals, catch fire, or even explode. You may think that my welds look pretty rough, that's because they are :).
Final note, I used to be able to vacuum 1 room, now I can vacuum the whole house on MAX setting and still have 75% left.
P.S. Some Dyson battery BMS are programmed to brick if the voltage drops below a certain level. Disconnect the BMS at your own risk. You may want to make before you break just in case :)