We've all seen those little feet that extend out of our keyboards, but did you ever ask what they're really for? It turns out they're not there for ergonomics.
I recently got a new keyboard and realised I never knew whether I was supposed to extend those feet or not. After a little research, I discovered that they're usually there not for better ergonomics but to make it easier to see the keys. This little post from keyboard maker BakkerElkhuizen explains it well:
First of all, it is important to distinguish between people who can type ‘blind’ and people who cannot (who use two fingers).
The advantage of extended Feet for non-‘blind’ typers is that they can see the keys more easily. There are no disadvantages of extended Feet for them.
But things are different for people who can type blind, as they do not look at the keyboard while typing. The Feet do not therefore need to be extended. In fact, extending the Feet can put one’s wrists at risk if they are angled back too far. For this reason, blind typers can best keep the Feet retracted and use a relatively thin keyboard. Various studies even have demonstrated a beneficial effect when angling the keyboard away from the user (with a negative incline).
So, if you have to look at the keyboard when you type, extending your keyboard feet (or making some of your own) can be good. If you can type without looking at the keyboard, however, you're ergonomically better off ignoring them (especially on newer keyboards). If they aren't comfortable flat, your chair might be too low -- try adjusting it higher and you should notice a difference. Hit the link to read more.
Feet in or out [BakkerElkhuizen]