Given that the Spongeface kit is a little narrower than the holster itself, I ended up using a two part epoxy to fasten a snap on the back of the board and snap it to a holster. I also added two small strips of Velcro to either side for stability. Definitely not going anywhere, but easy to remove if I need to change the battery.
Link to Tyger Cheex Gizmo holster
Any questions ask away!