It appears to me that Datahand is not for people with medium/small hands, I`m saying that because the thickness of the switches and distance between the clusters/switch assembly will force the user to uncomfortably spread fingers to touch the center/down switch or pinky/left and index/right.
For example my hand is 7 inch long, measuring from wrist joint to tip of the middle finger, according to the pictures and measurements I found about DataHand, I would not be able to use the device comfortably.
Part of the challenge is to make the 5 way switch no bigger than 1 inch width/height and keep it serviceable. People with extra small hands... sorry, having Michael Jordan`s hand size would solve lots of design problems
@RSanders or anyone that own a DataHand, do you happen to have large hands/long fingers ? And thank you all for posting pictures of the original device.
The keymouse... the trackball version is $500+..., the mouse version is not even worth talking about, you cant destroy your shoulder constantly moving half pound piece of plastic on the desk...
For that money you can get a cheap 3d printer for $150, micro switches max $20, one roll of filament whatever color you want $15, soldering iron, wires/solder/flux $40, teensy $20
And you can customize it, modify the 3d file and print parts as you please, make modifications to fit your need, hang in there, we`ll get this 
I will have some additional measurements for you shortly beyond what has already been posted. Regarding hand size, the measurement from the base of my palm where it connects to the wrist to the tip of my long finger is essentially identical to you, i.e 7”. In my opinion, smaller to mid sized hands would have an easier time with the DataHand than someone with large hands and correspondingly thick fingers, mostly as relates to accidental/incidental key activation. What you may have been missing from not having access to an actual unit is that the PCB to which the key wells are attached is fully adjustable in the x, y, and z plane using the two numbered dials pictured (for adjusting distance of left and right corners of the PCB in relation to the palm pad) and the thumb screw pictured for elevation (one on each side of the unit for independent elevation of the left and right side of the PCB). The PCB is not visible as it is protected by what amounts to a rubber dental dam. The rotational position of the PCB board has a big impact on comfort, at least for me. It effectively reduces the horizontal distance with which you were concerned between the fingers. It is much easier to curl the fingers towards the palm than it is to spread them, as you have observed. On mine, the left hand PCB is rotated counterclockwise slightly and the right hand one is rotated clockwise slightly. Tenting is also important. On the left, my pinky is lower than my pointer finger. On the right, same thing. To avoid unnecessary reaching and other contortions to activate keys, I requested tall keys for all except the south directions, as described below. The best way to describe this is for most west or east movements, I very slightly move the finger in question towards the west or east while at the same time very, very slightly pivoting my entire arm (forearm, wrist, hand all as one unit, pivoting more or less on the elbow or whatever is being supported by the arm of my chair) in that same direction giving just enough movement to the finger to activate the wanted key without activating any of the other west or east keys at the same time. I added pads as needed to further decrease necessary travel, as specified below. It is important to note that, while the original design was intended for multiple users (each user making note of their respective dial settings or thumb screw settings), a properly and extensively configured DataHand, like mine, is a very individual thing and once set up "just so", it is not easy to convert all the adjustments, key heights, palm pad size, key padding, etc. over for another individual to use.
The rubber palm pads came in two sizes, small and large. I personally use the large. The base unit also came with North keys tall and South West East keys short. I requested tall keys for all except the South direction as I had problems actuating the west and east keys otherwise, especially at speed. I also requested the oversized thumb up keys as I kept missing them at speed. Of note, I am slightly slower on a DataHand than on a regular flat keyboard, where I was timed by a temp agency at 120wpm in my prime. I was closer to 80 to 90 wpm on a DataHand. This is due to reaction times being faster if your fingers are hovering over keys as opposed to being in physical contact with them prior to activating your finger to activate the key. At one point I was working with DataHand engineers as I was outpacing the processor when switching between NAS mode (numbers and symbols) and normal as well as switching from typing a capital letter followed immediately by lower case. The unit would keep typing all caps even though I had released the shift key because I was typing too fast for the processor to catch that the shift key was no longer depressed. Same with NAS, I would type a number, release the NAS key, and numbers/symbols would continue to be output as I had outpaced the processor. For most typists this is probably not an issue but for a, at the time, high output medical transcriptionist, it was a big deal. Now I don't have to type that fast or for as long so I don't worry to much about speeds. The issue was never satisfactorily resolved other than to limit the string of all caps to one cap after the originally intended cap or one number/symbol in addition to the initially intended number/symbol. Editing still became necessary so it really wasn't a fix as far as I was concerned. I just learned to slow down when shifting between lower case/upper case and when typing in medication dosages (switching rapidly from numbers to letters). Even with a slightly slower speed on the DataHand, my output actually increased as I did NOT need breaks while using the Datahand. On any other keyboard, including Maltron and Kinesis, I still need periodic breaks as discomfort does develop when using those, just not nearly as quickly as when using a regular flat keyboard.
To further decrease necessary finger travel, I also requested the rubber adhesive pads to put on all the nswe keys and the thumb keys, most of which have long since deteriorated and have been replaced by industrial strength adhesive loop side (not hook side) Velcro.
The duct tape visible was me being lazy and not bothering to remove some deteriorated rubber pad for replacement with loop Velcro. I may get around to it at some point. The mostly missing (a warm thank you to the nighttime cleaning staff for that "modification" which essentially turns it into the original stock thumb up key) thumb up key is directly opposite the duct tape and, as it is only needed to toggle back to “normal” mode, it is not too much of a bother to pause a moment and reach a bit to actuate it when needed so I have not bothered cobbling together a replacement. If I were still in a high production medical transcription environment, I would have fixed it by now.
The intact right thumb up key is included for comparison only.
Thank you for your thoughts on the keymouse. I will avoid for the moment.
