I work in a school and to make the Adventurer safer to keep in a classroom I have installed a carbon filter on the extraction fan (I only use PLA) and have now installed a lock on the door.

To create the hole in the door, I used a step drill (do NOT use a regular twist drill on plastic as it WILL crack) to make a hole smaller than I needed, then I used a flat file to get flats on the top and bottom and a round file on the sides. Masking tape helps protect the plastic from scratches (although I actually scratched the door afterwards when using pliers to tighten the nut!).

I used this lock, which has the dimensions on the listing. https://www.amazon.co.uk/FOGAWA-Security-Furniture-Cylinder-Cupboard/dp/B082PD6W93/

This just slots into the hole behind the screen where some people have created mounts for temperature sensors. Depending on your printer/material, you may need to increase flow or size to get a nice fit.

Now, this thing actually doesn't need to exist as I've realised that if I had just made the hole nearer to the door, there is a 1cm lip on the case that the latch could catch on. Unfortunately I didn't realise this until after I had made a massive hole in the door! :-)

I'm also aware that the lid is quite easy to remove, so this lock isn't super-secure, but most children won't be aware of that!

You WILL need supports to print this, that's where there is a random flat plate for the supports to rest on so you don't need a brim. The Thingiverse model orientation is strange, but you can see a photo of how to print it.