I designed this for 2 purposes:

1. Store interesting/study slides. 
2. Store the case that is waiting for more investigation (IHC, deeper cuts, etc.)

The slides are stored vertically, so that the label is upward and can be easily read, and you can quickly browse/shuffle through the pile of slides in this manner (like flipping through index cards)

The box has 5 large slots that can be divided into 4 slots each, so there is a maximum of 20 slots available. You can adjust the amount and space of each slot using the divider plates. 

There are 2 options: with lid or w/o lid
For storing study cases, I recommend the lid option to prevent dust. But for cases that are pending some investigations, putting slides in and out every day, the lid might not be necessary.

As for the lock, storing lots of glass slides makes this box quite heavy, and I think it is best to use a metal lock rather than a printed one. I have attached the dimensions of the lock I use. I think you can easily find this on Amazon, Taobao, or other online shopping platforms (I bought mine from Shopee).

You can use metal screws to secure the lock, but I don't like them sticking out inside the box, so the printed version is provided. Here's how to use it.

1. Put the printed screw inside the box (screw head "inside)
2. Fix the position with a tape
3. Put the lock outside. The shaft of the screw goes through the hole in the lock
4. Use a soldering iron to flatten the shaft that sticks outward. The excess plastic will fix your lock in place.
5. Remove the tape
6. Finish!

No support is required.