DIY Midi controllers

https://djtechtools.com/2015/08/25/how-to-make-your-own-diy-midi-controller/

https://djtechtools.com/2016/03/06/converting-old-cdjs-to-midi-controllers/

https://www.ebay.com/p/Behringer-Bcd3000-bcd-3000-Midi-USB-Mixer-Control/1719791957?iid=162331538142&_trksid=p2047675.m4097.l9055

https://djtechtools.com/2017/04/26/cheap-dj-gear-for-the-thrifty-mixer-low-cost-hardware/