Might be a neat idea to offer a magnetic mount for it, like a flexible flat magnetic board shaped to fit the TRMNL with a sticky backing so you can attach it somewhere and then use that to attach the TRMNL (your site doesn't seem to say anything about being magnetic so I'm guessing you have to attach magnets to the TRMNL too though?).
For that matter, the site doesn't offer any information about mounting it at all. Looking at the disassembly animation I see what looks like a hole to hang it on a nail, but it might be nice to put this info at least in the FAQ section if nowhere else (that does say it can be "hung on a wall" but no details).