I also use an empty broth can. I keep mine out of sight in the bathroom cabinet and the small size it by due to the small size it doesn't take up much room. I also dressed it up a bit by covering the bare metal with white duct tape and used a sharpie to mark "Razor Blades".
I used an empty broth can for years. I painted it with black rustoleum and used it until it was filled up. While I was slowly filling the broth can, I received 3-4 small empty blade holders with orders from different companies as a freebie. So now, I am slowly filling those little freebie blade cans up. When they are finally all used up...? I will probably go back to a broth can or 3D print something for the purpose.
I use an old box that used to contain screws. When it is full, I guess I'll tape it shut, write a warning on it and just toss it.
When I started wet shaving late last year, I took the box that my shaving brush came in and cut a slot on the top. Then I took my daughters glue stick and glued the box shut. It is still not full yet. Not sure what I will do one it is completely full. I guess I will need to read the rest of this thread for some ideas.
The slots in the bathroom wall concept is intriguing to me. Imagine the loads of vintage blades hiding in these old houses. Maybe I'll cut my way through the wall of an old house and record a video shaving with one of these bad boys. I kid of course. I'm ignorant and senseless but not completely 100% stupid.
The house my wife has been in for 32 years, and me for 15 underwent a major restoration, much to the dismay of my lower back, which stretched about two years. All floors refinished, all wallpaper torn/steamed off, paint all over the place, tiles, fittings, door hardware, you name it. Well, when replacing the medicine cabinet in the upstairs bathroom, installed around 1952, guess what I found? You may have guessed, a pyramid of DE blades about 5 inches tall and a foot wide at the base, whose apex met at just the point of the slot in the back of the cabinet. Great idea really; too bad the new cabinet didn't have one; just going to have to tear the house down and start over I suppose.