Theoretical mixers design.
When looking at interesting mixers I came across a mechanical engineer that does animations.
Some may not be very practical, but it kinda cheered me up that there are still people out there thinking up interesting solutions.
Artofex like mixer. https://www.youtube.com/watch?v=6ktLcEOzY9o [1]
https://www.youtube.com/watch?v=gYksowpfhFY [2]
2 speed whip https://www.youtube.com/watch?v=ZJdrYD-DPnM [3]
One arm reversing. https://www.youtube.com/watch?v=iNl0R_26HSE [4]
One arm speed change. https://www.youtube.com/watch?v=E_QsGY1Rz7E [5]
One arm. https://www.youtube.com/watch?v=M4zgWuNkLrA [6]