The closest I’ve come to a design manifesto is this list of rules for my design work.   They’re not really rules, more like guidelines...

1.  Don’t give to the ear what’s already given to the eye.

2.  To participate there are three useful actions: make a sound (which can be in tune, in time or in tone), keep silent,  show restraint.

3.  Every parameter you can control you must control.

4.  Honor your error as hidden intention.

5.  If you look out of a window and see a mountain, you can’t look out the same window and see an ocean.

The above are extracted and bent to my will from Andre Bresson, Robert Fripp, Wendy Carlos, Brian Eno, and Charles Ives.