M vs C

Mostly Printed CNC - MPCNC Advice
1

What’s the difference between the TopM bottomM CornerM and the norman Top Bottom and Corner Peices?

2

Mirrored

3

what’s the advantages of using mirrored parts, 2 sets of each

4

It does not work that way, 2 of each. Have a look at the build instructions and it might more sense.