Adding extra HID 'buttons' to my pc

Hi I want to make a ‘push-to-talk’ button that doesn’t use any usa/uk keyboard standard keys. I use all of the standard keys for my voicebot commands e.g. saying ‘reload’ presses the ‘r’ key. I need to have a physical button that doesn’t use a key that a game may use or one that can be changed easily.

I have found a device called X-keys® USB 3 Switch Interface which seems like it would work however their website doesn’t say anything a uk shipping and doesn’t use paypal and on amazon it’s twice the price. I also don’t know if I can use the F13-F24 keys as my keyboard doesn’t have those physical keys I assume those keys are still there in the OS.

I am willing to build it myself and learn what I need to know. I would be grateful of any information anyone can provide.

Note: I am disabled so I use voicebot for accessibility reasons and just so you know im typing with windows osk.

If you can make use of a serial input you can make your own board with custom buttons with an Arduino. That will require some programming and tooling to have a nice finished product but it’s way cheaper than any device.

I would also go with an Arduino. If you are going for a Board which supports USB natively (the Micro does, the Uno does not) you can program it to emulate a HID device. Copy-and-paste ready example code does exist:
Emulating a F13 keypress should work on any OS, the key is found on very few USB-Keyboards, older full width Apple keyboards for example.

I have been working on this for a while with this touchscreen display:

a USB to UART adapter, a USB-A to USB internal header, and Python.

They have a graphical IDE that makes it pretty easy to have what’s essentially a functional mockup.

It’s a bit different from what you’re asking, but does the same and allows for detailed visual feedback via the display.

For a PTT key, you may be better served by a button with tactile feedback, but the display is great if you want it to be multifunctional, or maybe flash green when it’s enabled, or whatever.

Your reply’s have given much to continue with, I will go with the Arduino Micro as you all suggest.