If you hold up your empty hand you will find that your thumb can comfortably oppose any of your other four fingers in a pincer grip. This suggests that a board

If you hold up your empty hand you will find that your thumb can comfortably oppose any of your other four fingers in a pincer grip. This suggests that a board should have at least four keys that can be pressed with the thumb while the fingers type without any strain whatsoever. My ideal keyboard would be shaped to accommodate the neutral state of the hand. Hitting modifier and a key should feel as comfortable as a natural pincer grip. I certainly don’t want to use my weakest finger to hold a modifier key, even if it’s on the home row. I’d try to squeeze a fifth thumb key in if it could be ergonomic, so as to have control, meta, super, shift, and space all on the thumb. The Kinesis Advantage 2 comes closer than any other board I’ve used. I’m not entirely satisfied with the lack of adjustability of the thumb cluster though. Not everyone has the same size hands after all. It’s fairly comfortable at lap level though.