Mine would be creating pen and paper ciphers for my made up secret communication needs.
If you’re familiar with the Lock Picking Lawyer, he has his own store and has some good kits.
https://covertinstruments.com/collections/lockpicks/products/learn-lockpicking-bundle
I’m not getting any sort of kickbacks from the link. I picked one of these bundles up and I like it. The lock it comes with is super handy because it’s designed to be re-pinned. You can change the pins without disassembling the entire lock.