Ever tried typing mathematical equations in your code IDE, email, or on Slack? You might know it can be tricky. Mathpad solves this with dedicated keys for Greek letters, calculus symbols, and more. Press the ∫ key and get ∫, in any application that accepts text. It uses Unicode composition, so it works everywhere: Browsers, chat apps, code editors, Word, you name it. Basically, anywhere you can type text, Mathpad lets you type mathematics.
I built Mathpad after getting frustrated with the friction of typing equations in e.g. Word, and what a pain in the ass it was to find the specific symbols I needed. I assumed that a product like Mathpad already existed, but that was not true and I had to build it myself.
It turned out to be pretty useful! Three years of solo development later, I'm launching on Crowd Supply. One of the trickiest parts of this project was finding someone who could manufacture custom keycaps with mathematical symbols. Shoutout to Loic at 3dkeycap.com for making it possible!
Fully open source (hardware + software): https://github.com/Summa-Cogni/Mathpad Campaign: https://www.crowdsupply.com/summa-cogni/mathpad Project log: https://hackaday.io/project/186205-mathpad-the-math-keypad
Ideally you want access to everything without moving your hands off the keyboard. The DIY keyboard scene makes a lot of use of layered keymaps. It seems like the endgame for this kind of thing is not separate "keypads," but rather wider support, standardisation and adoption of multiple-layer keymaps. Half the problem is designing good maps and the other half is learning them. Sharing maps, and better software for learning/practicing the maps would help. Then you might need a few more keys to select layers. A minimum implementation might be adding a two thumb buttons below the space bar to select layers.
EDIT: inserted more text
The main slowdown I face as an occasional TeX user is remembering the TeX names of less frequently used symbols. For that purpose there is detexify (draw the character and find the name, doesn't work all that well) but a popup graphical menu or (if you must) a phone app would be fine.
(Or use Unicode search extension for Raycast—like I do—which is fundamentally the same as googling, but with fewer key presses.)
[0] https://en.wikipedia.org/wiki/Compose_key
[1] https://github.com/SamHocevar/wincompose
[2] https://github.com/Granitosaurus/macos-compose
But that's exactly the same issue with the hardware solution - you can't use Ctrl+F to find by name and you can't see all the many symbols on the keyboard itself. You'd need a software solution to show a visual searchable "cheat sheet", and also you can map more mathy keys to an existing bigger keyboard, where entering some symbols will be way more natural, e.g., for greeks you can map most of them to different A and B latin keys instead of having both αβ on the same key. Similarly, you could do map ℤ to Z and ℕ to N, so these would be simpler to remember/input than using a dedicated keypad, so the printed symbols on the keypad aren't that useful anymore.
* the way unicode input works in qmk is pretty janky imho. this is not something you can plug into any random computer and expect to always work perfectly without doing any configuring.
* you can accomplish the same thing if you have qmk (or similar) based keyboard by throwing the symbols on another layer or whatever you prefer. for $140 you can get a whole keyboard.
the keycaps are a nice touch though
Question: the description says it has access to all the Greek alphabet letters but only the lower case ones are shown on the keypad: do you get (e.g. ∆) by using the shift key on the regular keyboard plus δ on the Mathpad?
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With 3 modifier keys, this offers 8 potential modes. What's done with the other 2?
Why only 12 keys and 3 modifier keys? Granted, 6+ modifier keys of the SCK is probably 1 or 2 too many.
Also, I miss graphing calculators / CAS like the HP 48 where math symbols were (usually) easier-ish to access.