I have actually inherited from my father this tool , back to 1985.
Its the perfect tool for cutting hard plastic , I use this tool to trim ( plastic channels ) the ones that you install cables in them .. and you mount them on the wall surface.
Any way this tools its a killer , to trim very small PCB , its does a clear cut in everything equal with the length of the master blade , that is 4cm long.
For larger ones I use jigsaw , with special blades , the ones for clear cut on Plexiglas.