Intricate footwork
Many machines require the Base to do intricate footwork. I like this type of challenge.
A great example is the innovative transition I created for the I:
The same transition is done twice to make the simplest symmetrical machine, the I Infinity:
The transition from Mono Throne in Smallemoi:
The transition to Outside Star in Ouroboros:
The I/O transitions:
The Rewind I/O transitions:
The Spice transitions: