It would be interesting to have a trackpoint like option for pocket MNT reform. in the middle of the keyboard. Although perhaps the same could be said for the regular MNT reform.
The trackball is nice, its just the location could be better. If this isn’t going to happen, no worries. Just thought I would make this suggestion.
This comes up from time to time from people who are used to Thinkpads. Unfortunately I was never a big Thinkpad user so I don’t really “get” trackpoints and thus my motivation to work on this is relatively low. Also, existing solutions normally require a number of custom partially cut-out keycaps for the trackpoint to fit, and I didn’t look at the footprint of any trackpoint modules to check if they would fit between Kailh Choc keyswitches. I’m pretty sure that on Pocket Reform, which has densely packed keyswitches, there’s no room.
That being said, MNT Reform is an open hardware project and anyone can mod and fork the keyboard(s) or do some 3D modeling with STEP files from trackpoint manufacturers to check if it would even make sense mechanically.
Yeah, its just habitually easier. I am sure your trackball is of similar use though.
But I appreciate your response. Perhaps there isn’t room, but I was curious if there was. Anywho, thanks for the reply.
Even as a long-time ThinkPad user who always preferred the trackpoint over anything else, I have found that the Reform 2’s trackball is easier to use in the most of situations.
But the Pocket’s trackpad is smaller so I’m curious if my experince will be the same.
I have been a long-time trackpoint enjoyer as I used various thinkpads models for about 15 years as my main laptop before I switched to the reform. So I understand the excitement. I much prefer a trackpoint over a touchpad because it allows my fingers to stay on the home row while operating the pointer. Since the MNT Reform Trackball also has this property, I’m not looking back much.
But… today I disassembled some old Thinkpad keyboards I had floating around and this let me come back to this thread. It seems that the trackball of the Thinpad T440s keyboard uses the PTPM754DR controller. Searching online it seems that this chip is quite popular among Thinkpad keyboards and there is a large community of people who have re-used the Thinkpad trackpoint for their own hardware hacks. The pin-out is quite simple and there is a collection of them that can be found here:
https://deskthority.net/wiki/TrackPoint_Hardware
If that link should vanish, it’s essentially a PS/2 connector and some lines for three buttons which are unused in this design. On the photo below, from top to bottom the pins are: Data, RST, Middle, Right, Left, CLK, GND, VCC and rest unused.
Doing something similar for the Reform Keyboard might be challenging because of the space restrictions:
Even if you cut the circuit board that the trackpoint sensor sits on, the housing of the switches are too close together. Not only the keycaps would require some material to be removed but the switches themselves as well which I don’t think is quite nice. Then, the mechanical switches are quite high. You’d need quite the long stick for this to work and I’m not sure the sensor is designed for that.
Lastly, for this to be a sustainable solution, it should be possible to buy these components from somewhere without having to scavenge on thinkpad keyboards. I have not yet found the sensor itself online.
EDIT
Actually… It might be possible to pull off this mod by using a labret cheek piercing as a very thin stem. Yes, really: GitHub - alonswartz/trackpoint: How to integrate a trackpoint in a mechanical keyboard
EDIT2
But… there seem to be some traces exactly at the point where the hole should go. So any such mod would require creating a new keyboard PCB:
EDIT3
So… the plot thickens. Suppose somebody would produce some custom designed keyboard v3 with a hole at the correct location then there actually is at least one supplier of pointing stick sensors and PS/2 module board:
And there are people who published how they used this together with a RP2040 to build their own custom keyboard with trackstick:
@minute turns out that “anyone” was you after all!
Thank you! Once the keyboard is out, we can start to try some drilling. 
So he is actually going to make a trackpoint keyboard?
Surprising. I do like the idea, but I thought it wasn’t going to happen. This is a nice surprise.
No. But keyboard 4.0 makes it easier to start hacking a trackpoint into it.
Keyboard 4.0 can be ordered now:
So any trackstick nerd can now try and drill a small hole into the board poke a trackstick through. I have my own sensor board already waiting. 
The trackpoint supplier is a good find.
I think you would not have that much problem mounting the trackpoint on the ortholinear big keyboard, there is even a column of blank space in the middle. On the other keyboards it would be more challenging.
The other point I noticed while using my old notebook is that on select IBM and Dell machines you wold not get left/right mouse button but rather bigger top/ smaller bottom. This makes it easier to recognize the primary button, and makes it trivial to switch between left/right-handed use because everything is centered. The sprawl of buttons around the trackpads and trackballs, on the other hand, is not that great.
If you ever get it working for a pocket mnt reform, people may wish to buy one from you provided it is done right of course.
If trackball is better, maybe I wouldn’t need it. But it would still interest me somewhat.
One of the ideas that’s rattling around in my head, and which might get implemented in the RPi5-based Tandy Model 100-esque laptop I’m slowly building is to stick a ThinkPad Nipple into the middle of the keyboardio Atreus. I haven’t cracked the case on my Atreus yet, but there’s a ton of space between the two halves of the keyboard, so I figure I ought to be able to make something work. I’ve also got a Reform Keyboard on order. We’ll see how things go between now and the end of the year.
I posted an update to this story to the fediverse in October and failed to update this thread with a status update. Apologies for that. Here is the post: josch: "@mntmn@mastodon.social Well, it "works". It's jus…" - FLOSS.social
minute routed the traces of the Reform Keyboard V4 specifically to make it possible to drill a hole at the right spot without damaging the traces when I asked them for it. It is also thanks to MNT that I have this keyboard without switches for performing this experiment. Both keyboard as well as the trackpoint module are recognized via USB and work as expected.
The prototype can be seen in the photos. There is a 3D printed stem which you stick through a hole in the keyboard PCB. The trackpoint sensor can be found in different varieties online. Some of the keycaps needed to be modified of course. Remaining problem is the fragility of the stem which is made of PLA. A thinner stem would be better and would avoid having to file some material away at the corner of the switches as well.
Why am I posting this now? Because there is a new status update. gordon has now created a new PCB design with holes for the stem and mounting screws at appropriate positions:
I created a mock-up of the physical parts of this design in openscad and will print it to continue testing the mechanical design and to get keycaps with appropriate circular cutouts manufactured:
$fn=32;
width=33.6;
height=32.6;
padw=15;
module pad() {
translate([2, padw-7.5, 0]) cylinder(h=4, r=0.851);
translate([7.5,padw-7.5, 0]) cylinder(h=4, r=1.715);
translate([13, padw-7.5, 0]) cylinder(h=4, r=0.851);
translate([7.5,padw-13.4, 0]) cylinder(h=4, r=1.016);
translate([2.5,padw-11.23,0]) cylinder(h=4, r=1.016);
}
module keycap(x, y) {
difference() {
translate([x+padw/2, y+height-padw/2, 6]) import("/home/josch/Downloads/mbk_keycap_1u.stl");
translate([width/2, (height-15.61), 0]) cylinder(h=20, r=4.5);
}
}
difference() {
cube([width,height,2]);
translate([0,0,-1]) {
translate([18.6, height-15, 0]) pad();
translate([9.275, height-15-17.6, 0]) pad();
translate([0, height-15, 0]) pad();
translate([width/2, height-5.61, 0]) cylinder(h=4, r=1.1);
translate([width/2, height-15.61, 0]) cylinder(h=4, r=2);
translate([7.475, height-19.26, 0]) cylinder(h=4, r=1.1);
translate([26.125, height-19.26, 0]) cylinder(h=4, r=1.1);
}
}
#keycap(18.6, 0);
#keycap(9.275, 0-17.6);
#keycap(0, 0);
I (again) forgot to post another update here and only talked about it in IRC. I since bought the SK8707-01-005. Datasheet here: https://mister-muffin.de/p/rJQX.pdf
Conveniently it has a stem attached to it (so no glueing of labret cheek piercing needed) and I got several stem extensions with it so that we can pick the perfect length at the end. This is how it looks like when assembled:
A remaining issue is that the trackstick has some residual glue at the base of the trackpoint stem, so either the hole in the keyboard needs to be made even bigger (this is becoming difficult) or the bottom edge of the trackstick hole in the keyboard needs a little bit of chamfering.
I am now looking into the best way of how to connect the SK8707-01-005 to USB electrically. Maybe I get a RP2040 and flash QMK with a PS/2 driver to it?
If somebody has an idea of a simpler way to connect the trackstick’s PS/2 lines I’d be all ears. 
