Supports required to prevent frame locker from fusing to rest of frame.
Lefties need to mirror all parts (except pin obvs).
The frame work with PLA, however ABS is better as it will hold spring tension better.
The blade and pin work fine in PLA.
If you print in ABS, you may need to scale down the pin slightly and glue it in place as it may crack the frame when you press it in.
Post-Printing
Run a knife or sharp spatula around the frame locker to free it.
Run a thin tool e.g. screwdriver through the frame to remove support material.
Glue both sides of blade together (aligning the halves after assembly is easier).
If you printed in PLA, store the knife open to prevent the frame from losing its tension.