YA36 is a 36 keys split-ergo low-profile keyboard designed to fit my own (strange shaped) hand. Although I don't think any other people can type on this specific design comfortably, there are some findings I think may worth sharing.

The idea of angled columns comes from an observation I made when I considering a question "why no matter how much I increase the pinky stagger or decrease the key spacing, I could never comfortably reach the top row pinky key," which is moving the fingers (except middle) straight upward is very unnatural. If you try to make a fist and then release it, you will find your finger moving along an angle. Thus I think making the columns angled may lead to a more natural muscle movement. Then to figure out how much I should angle the columns (and also the amount of column stagger), I dipped my fingers into some pigments and simulated typing on a sheet of paper (but instead of following the normal keyboard layout, I let my fingers stretch naturally). The result is about 8 degrees between two adjective fingers, and the middle finger worked as the centerline (i.e. no angle, parallel to the forearm). Because of this design, reaching the top row pinky key is now effortless, reaching the top row keys of index and ring fingers is also become easier, and surprisingly because the key spacing is reduced, reaching the extra index column is not difficult (if not easier) even with the angle.

Usually the spacing between the keys on most of the keyboards is 19.05 mm (or 18 x 17 mm for choc switch), but since every person has a different hand size, you may find that the standard key spacing may not suitable for everyone. This is especially a problem for me since I have a very small hand (16 cm length). When using a normal keyboard, I always found I'm tapping on the edge of the top and bottom row keycaps instead of the center, which is uncomfortable especially for those sculptured profiles. After testing several different key spacings, I found that the 15 mm spacing (the smallest possible spacing for choc switch) works best for me. However, one thing that needs to notice is that the smaller the key spacing is, the more accurate the column stagger need to be. The reason is that the area of the top surface of the keycap would become smaller because of the smaller key spacing, which means that it would not be as tolerant as the bigger keycaps when you cannot tap on the center of the keycap (i.e. tap on the wrong key vs. tap on edge). So if you have a small hand but have a bad experience typing on a small key spacing keyboard (like the one on a laptop), it may not be the fault of the key spacing itself but the problem of the non-ergo layout.

Because my index finger is longer than the ring finger, and it naturally located at a higher position than my middle finger when I curled my fingers and lay them on a flat surface. However, what I want to say is that sometimes we would stick to the 'common' design and didn't notice that our own hand may very different from other people's. When I just started to design my own keyboard, I always place the index column lower than the middle column, and only tried to figure out how much lower it should be, because all the column stagger keyboards I saw looks like this. Unfortunately it does not work for me. My index finger always feels that it is not in the correct position. But one day when I looked at my curled up fingers, I suddenly notice that my index finger is higher than the middle finger. Although I'm not very sure if a higher index column would work or not, I anyway gave it a try, and the result turned out very good.