>>78281
Hmm, after another look I'm pretty sure those barrel plugs are for the vibrators, not the battery, but, I'm not sure.
>>78291
1. Honestly, I don't have a solid reason for this. I would assume he's working with the same supplier as he could get better rates and a better chance at custom parts, and as such I assumed that the custom parts he's getting are very similar to the model I linked, but that might be completely false. There's a chance he's just getting the controllers that have barrel plugs where the motors would be, and getting the motors and shells elsewhere to assemble his own attachments. There do seem to be some nice motors out there with barrel sockets (
https://www.aliexpress.com/item/3256805921343250.html) but I can't find any that look like his attachments.
2. I'm not sure. Glue would probably work, but then you'd only get one shot at it. You could use small zip ties, but that's a bit janky.