Maybe wind the misplaced sarcasm down several notches please, it's unseemly particularly as knife making is easily one of the more popular goto shop projects in high school (outside the STEM nerd and theatre kids circle, I know) and that "wannabe gangsters" even in their teens have easy access to stolen goods at a discount or often five finger their own.

UK (and Canadian, Australian, etc) weapon disposal schemes frequently land home made weapons eg: https://kk.org/streetuse/english-ownerbuilt-weapons/ from 2006 is barely a trickle of the flood that gets swept up by amnesty programs.