controller mount

New to the site and can't figure out the best way to ask a question. Apparently I lost my compression nut that mounts the tablet holder to the controller, anyone have ideas where I can get a replacement? Thanks.

After the maiden flight I released really quickly that the one thing that will drive me crazy is the lack of balance on the radios neck strap mount, most probably due to the screen mounting attachment. I therefore needed to whipped up a quick solution for this! I had some thick fishing line...