I finally got my chocofi keyboard build working and then immediately felt like I wanted it lower - closer to my lap. Part of the idea of keeping my desk in perpetual prototype mode is that I feel empowered to do things like cut a tray out of it - so I did.
It worked ok on my lap - a little slippery. But then I had the idea I could put a monitor mount upside down and use a monitor arm to hold the keyboard.
I'm happy with the result. It's got a little wobble to it, but my legs generally support the side. I might try some individual tripod + magnet mounts in the future.