There is an Institute for Legislative Action (NRA-ILA) report in the April issue of the American Rifleman (page 88, "When Laws Collide: Federal Pre-emption and State Firearms Freedom Acts) regarding this type of thing in terms of firearms manufacture and sale. The implications of the jurisprudence seems to be relevant as well to the States' marijuana laws and possibly knife laws.
The difference, as I see it, is that the knife law requires actual transport across a state line to be illegal.
Now, if you want to really be safe, I imagine that you could order the blades from company A, the handles from B, then manufacture the opening equipment, to include drilling a button hole into the handle, in state for final assembly.
Rereading my post, I get the impression that I was more making a "switchblade kit" advertisement with the implication that somebody in the state of Colorado orders a "switchblade kit" which is then mailed to him. This was not what I intended. I was picturing more that Company A orders parts from Company B, and possibly more companies, then assembles the knives in Colorado for sale in state.
IE A orders a big box of blades, and a big box of handles, and a big box of other parts...