I wanted to participate in an offroad event where a digital roadbook was required. I found in aliexpress a cheap bluetooth remote that I could use to control the roadbook, and then made this little holder for it.

It's not particularly ergonomic, but it got the job done. Leaving it out here for inspiration.

To mount it, you'll need 2 bolts ( I believe either M4 or M3) 20mm, and nuts. Alternatively, you can use zip ties.

To mount the controller, use double side tape or velcro.