I wanted physical knobs, buttons, and sliders to control my Pure Data modular synth, so I got an AKAI MIDI Mix. It is a reasonably priced controller with 24 knobs, 9 sliders, and 26 usable buttons. Unfortunately, AKAI did not fully document the MIDI Mix's MIDI support. Fortunately, people on the Internet collaborated to reverse engineer the MIDI Mix and document a communications protocol for it. I've written an object (midimix.pd) based on that document to use the MIDI Mix with Pure Data. The help file (midimix-help.pd) explains how to install the MIDI Mix and use it in Pure Data. You can download the files here:
https://github.com/nyponen/AKAI-MIDI-Mix-object-for-Pure-Data

BTW, I thought the MIDI Mix knobs were too short, so I designed and 3D printed new ones. You can download the STL file here, if you want to print your own knobs.
https://www.thingiverse.com/thing:6984802