A small cork might work, or a rubber eraser.

Monica, some spray bottles, things like hair spray or sometimes cleaners, or bottles that have those pop-up opening tops--anyway, sometimes they have a clear plastic cover. These are small around, like the size of a child's fat crayon, or chalk, not the big huge covers. That could make a good cover, held on with rubber band or tape. Also, sometimes you can get a cheap travel toothbrush holder, not one that covers just the toothbrush head, but the whole length, and put your x-acto into that. Just remember to put the sharp end down, so you don't cut yourself when you open the holder. Best of luck, I hate sharp things in the drawer or bin--they find my fingers every time!! Hugs, Marji

Cardboard to a custom length and width, duct tape to keep it closed. There's even pretty duct tape now.

I went into a smoke shop and they gave me a few cigar tube with a push on lid. Some are plastic and there are some that are of metal with screw lids. Look at your marking pens like a permanent marker we call Sharpie in the US. A piece of Styrofoam or rubber eraser stuck on the sharp end until you can find a safe cover should help keep you safe.

I use an empty Mini M&M container....has to be the taller one though.....peeled the label off and wrote on it with marker. I use them for lots of things.....beads, crochet hooks, lots of misc small stuff!