Thanks for the info. I plan to find an old key with the stem that fits and the flag a little longer than the hole. This way I can file it down to size and then impression the cuts. Being a two levers should make it quite easy. Old furniture keys are commonly found at flea markets for 50 cents or 1 euro each.
The problem is the trunk is at two hours drive from me, so I need to find an excuse to go there. Going there just to make a key is not an option at the moment. I’ll keep you updated.
Cheers 🙂