You can buy premade MIDI faders for about $25 [0], there's no way that the hardware aspect of this project is worth making over that. The software is the only real issue, at a quick glance, [1] appears to be relatively equivalent for generic MIDI fader support, perhaps with a few more bells and whistles available.
[0] https://www.aliexpress.com/item/1005005589381790.html (a chinese clone of the korg nanoControl 2, the original korg aren't that great quality, but they work, the clones are 'just as good', or you can pay more for korg or another brand)