Inspired by this thing:
It started out for fun, to figure out the mechanism... Having shown it off to my sensible colleagues, seeing it held in their hands, it made me realised how menacing this thing is.
Please use it wisely, it is nevertheless a neat practical tool, not meant to be used as a weapon. Thing holds a standard Stanley box cutter blade.
Print 100% infill, total print time ~4hours
Bill of Material:
1) 4 x M3 x 18mm countersunk screw, for securing the linkage
2) 4 x Nylon lock nut, if not available use thread-locking adhesive
3) 2 x M2.5 x 6mm countersunk screw, to secure the blade