I made one. A simple Arduino with on-chip USB interface, a relatively simple bit of code and I have a 200-click dial wheel and 6 buttons. Click the ‘X’ button and the wheel jogs X, click the ‘smaller’ button to reduce step size, ‘larger’ to increase. Buttons for X, Y, Z and A (I have a rotary axis too). Designed a small PCB to house all of this lot, and carved an enclosure from a piece of hard wood to mount it in. Plug a USB cable into the Mac, the other end into my ‘jog box’ and it all works. The issue then becomes that the sender software needs to have keyboard shortcuts that can be emulated by the jogger - I ended up switching to UGS because of this (and the visualiser display). Would be happy to share the design and code if people are interested. All in on materials about $15, and a good day of ‘hobby work’ to assemble.
@davidlan I have the Rii mini keyboard controller and it connects to my macbook pro just fine. I wonder what the issue is with why it’s not connecting? Are you getting an error or is it simply not finding it at all? I’m curious.