Here's a printable pedal body for the Ammoon looper that includes space for a 9V battery. I soldered a 9v lead to the circuit board and routed it to the battery compartment. It's surprisingly strong but obviously not gig-worthy.
Here's a link to the models in OnShape: https://cad.onshape.com/documents/31261737636ec3fc8be649c9/w/a0894581473a1f71d77f3201/e/f5072e4f5ff8dcf0c03479f5
It's been a while since I printed this; I think it needed a bit of trimming to fit the 9V lead properly. If I make another version it will include a spot for a simple switch on the 9v lead, since it seems to drain the battery even if it's not being used or even have a guitar cable plugged in. The base/body fit is not ideal either, but it works.
Note to Ammoon: I don't imagine this will be a problem for you guys, but if it is please let me know and I'll either remove your name from it or remove it entirely.