I didn't like the phrasing on the models I've seen, and I didn't like that those don't account for a standing person, and you have to bend to read what they say. This model covers it all. Just type your text in the slicer of your choice, and you're good to go.

Use glue to assemble.

Can print with multicolor systems. You can also decrease the height of the insert by 1/2 and extrude letters as separate layers on top of those - slides will still have some space to move through.
Or just use a sharpie. What am I? Your design advisor?

With very few edits, you can make it into a 3-4 labels model. Just print additional covers and inserts.

While I've made a profile for makerworld that SHOULD work, I strongly recommend to download STL and customize it yourself with OrcaSlicer and embedded text.