How would i make a device for sending keyboard input to a computer?

I have an idea for a new kind of keyboard, i think the best way to test it would be to make one and get it to work with my computer. If i can get each button on it to send a keypress signal like any other keyboard, i can work out the details with software like Kanata.

I have access to a 3D printer and i can make models in Blender, but i have no idea where to start with the electronics. Should i look into Arduino? Contact electronics manufacturers? How do i get from an idea on paper to a physical prototype?

I should mention, this thing is actually supposed to be a TV remote, because i think it's bogus how little typing on a game console or smart TV has evolved since the '80s. I said keyboard because that's basically what i'm trying to prototype, but normal mechanical keyboard hardware is rather bigger than what i'm trying to make. Little buttons my computer can treat as a keyboard would be a good step toward making a good design for a remote controller. Also, i am not a programmer. I know a little HTML and have dabbled with Inform6/7, but C and Python are magic wizard stuff to me.

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You could look into the mechanical keyboard world for what board to use or take apart a cheap keyboard.

Joe Scotto: How to Build a Handwired Keyboard (Note: YouTube Link)
The board he uses is a Pro Micro. The one he linked in his description is a micro USB version. You can find Pro Micro that has a USB-C connector instead.

I have access to a 3D printer and i can make models in Blender,
You will probably want to learn some basics of a parametric CAD program as well. I recommend FreeCAD because I'm a big fan of open-source and guaranteed long-term free access. However, Fusion360 and OnShape are also solid choices. Knowing how to make printable 3D models already puts you in a good place.
but i have no idea where to start with the electronics.
You already know the hard part.
Should i look into Arduino?
Short answer: Yes.
Long answer: It depends. If you don't know anything about programming (or are very comfortable with Python), I'd start with CircuitPython. This will allow you to concentrate more on how microcontrollers and firmwares for keyboards work, as opposed to learning the C/C++ Arduino syntax, which can seem a bit arcane at times.
If you're already comfortable with C-like languages, it might be worth trying out Arduino first to see if it is intuitive for you.
Whichever you do with, I would also recommend getting a bit of comfort with the other to increase your personal embedded toolkit. Personally, I prefer CircuitPython for proofs-of-concept and ad-hoc use cases (like when I woke in the middle of the night and hallucinated the smell of fire - I was able to setup a particle detector board in about 5 mins to prove to myself that there was actually no smoke).
Contact electronics manufacturers?
Unless you are already running a business that deals with electronics manufacturers, I wouldn't. At best, you'll likely get recommended reading lists, at worst, they might try to pull one over on you and/or steal your idea.
How do i get from an idea on paper to a physical prototype?
That will depend on the complexity of the electronics required and whether you need custom parts or off-the-shelf will work (and your comfort with soldering).
If you do end up needing a custom PCB, KiCAD is pretty simple to learn and will likely handle your needs for board design.
So, where to start?
I'd first learn how keyboards work. QMK, an open-source keyboard firmware, is probably a good place to start learning that side of things: https://docs.qmk.fm/how_keyboards_work
If you're familiar with Python, you might have an easier time learning and prototyping with KMK. Adding custom matrices is simpler than with QMK or ZMK.
For electronics hardware for prototyping I heavily suggest Adafruit. They have a ton of microcontrollers and learning resources. They have a while category dedicated to mechanical keyboards, including kits and some that allow learning without even soldering: https://www.adafruit.com/category/1020
Here's some suggestions for getting started:
Zero soldering
https://www.adafruit.com/product/4980
https://www.adafruit.com/product/4900
your choice of key switches and key caps.
Super simple soldering (two pins) with no wires
https://www.adafruit.com/product/5020
your choice of key switches and key caps.
- I would definitely not go with an Arduino. You want to send keyboard data to a PC, so you have to emulate a USB keyboard device. The run-off-the-mill Arduino only has a USB chip capable of being a USB serial (UART) interface - it is a seperate, single-purpose chip connecting the USB to the controller.
  What you need is a microcontroller board where the controller is also doing the USB stuff directly, so it is capable of being any device, at least those where a USB stack for the controller already exists.
  Maybe have a look at a Raspberry Pi Pico (which is not a "normal" Raspberry Pi, but a separate and rather cheap board with a small controller). If you google for "rpi pico as keyboard", you'll see a number of projects where people have already done this, so you might even get a ready-made software or at least something close to it.
  
  I would definitely not go with an Arduino.
  Arduino MCU? Probably not. There's better choices that are easier to use. Like the RP2040 (and RP2350) based boards.
  Arduino firmware tools and language? Definitely recommended. There are lots of libraries and a great community that one can turn to for help. Most common 32-bit MCUs (RP2xxx, ESP32, STM32, nRF, etc) have Arduino support.

It's definitely possible, there's a tool called QMK that will flash a microcontroller to send keyboard inputs to USB. I've made a few of these myself, they are just sometimes a little fiddly to get working.
This has a build guide for a specific keyboard, but you could pretty easily learn that and customize it to your liking.
https://github.com/abstracthat/dactyl-manuform

If you just want to control a computer, there are extant products for that. I have a device for controlling my RasPi that is maybe 10x15cm. It has a mini-keyboard, a thumb stick, a d-pad, and a touch pad. I have another without the stick and d-pad that is ~5x20cm. Some gaming mice have multiple completely reprogramable buttons.
If you want to have fun building, though... One of those mice could be an interesting place to start. It's layperson programmable. Has the ICs (kind of the hardest part) already made. You could rewire a few switches and design a shell.
edit: saw this

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