Working out the lesson I learned from my previous grip prototypes, that comfortable typing will only be possible with rigid support, I spent a little bit of time mocking up a grip design that braces against the forearm. It is bulky, but it feels much more comfortable than the palm-braced designs I have been making so far. I might make a second version that is lighter, adjustable, and foldable to see if it could be a practical approach for the final design.