Set out to design a little macropad from scratch earlier this year. The PCB came from JLCPCB and the sandwich case was cut at SendCutSend. The brass knob was turned by me. I soldered some white neopixels upside-down to control the per-key lighting; other than that, it's a bog-standard PCB design with an Alps encoder.
Adding the texture to the side of the knob is called knurling; there are specific tools you can use on a lathe to do it.
Size and volume are going to be your key factors. The PCB's for this project were only $2 for 5x with $15 shipping to Los Angeles. The case parts were largely inexpensive; I paid $50 for the lot. The acrylic layer was the most expensive at 20 bucks.
The most difficult part?
The most difficult part by far was the USB port cutout. It became a 2 set-up job on a 3-axis mill because I had to machine into the baseplate (need to find a lower clearance port to solder on). The upside-down LED's were also pretty shitty to solder.