[@HaltingBlooper] You can make thermite yourself, as the man in this video did, and make the canon yourself, as the man in this video did. Colin Furze is a plumber with decent mechanical knowhow. Carmen is a [I]engineering student[/I] with access to the labs and machines at the college. I think he'd be able to make both, no problem.

EDIT: References

[url=https://www.youtube.com/watch?v=9XAnx5x8E-8&ab_channel=colinfurze]Making thermite[/url]
[url=https://www.youtube.com/watch?v=uDm3is3PDc0&ab_channel=colinfurze]Making a thermite launcher[/url]