I finished the chordbars, but haven't built any buttons yet. I've tried two temporary solutions, and actually my first-try little yellow buttons were better than the current bigger green ones. It also sucks that I labeled the sticks on the stick, not the button (with little peel-and-stick labels). If the buttons are the labels, it's obvious which label applies to which button (duh), but you have to lift your fingers to see the labels. This way you can see the labels all the time, but it's hard to correlate which is which. Dilemma. I think the original machine's solution is that the labels are on the (slanted) front surface of the (quite tall) buttons. I think I like that approach, but it won't work with the "T-shaped" buttons I'm thinking of -- unless I'm significantly cleverer with the table saw than I think I am...
I was thinking that the buttons are typically way taller than they need to be, as evidenced by the mighty-thin yellow ones I made. But now I'm starting to think, conversely, that really tall buttons my relieve some of the wrist-tweak problems. You can rest the heel of your hand on the "deck" of the bank of chord bars, and if the buttons are, say, 3/4" tall, your wrist won't be so bent to push 'em. I'll have to experiment with that before I start cutting wood.