I change my blade at first skip. I don't save old blades. I toss in trash bin after sandwiching the blade in wide masking tape .I don't see the sense of storing old blades waiting to throw away.

One of my worst habits is not changing blades often enough. When I do I just shake my head at my stupidity. A new blade is so nice!
I put old ones in the containers they come in and write used or else I'd get mixed up, or I wrap them up in tape and toss.

I too put them in a case that new blades came in once I have an empty case until that time I have put them in a sharps container for my injectable meds. Nothing has been said about this as they certainly are sharp.

I'm with you, a sharp blade always feels so luxurious it makes me wonder why I didn't change it sooner.

I store old blades and pins in an empty tea tin. When it's full I take it to the drug store for the sharps container, although the pharmacist wouldn't handle my last batch so I just might find a container in a public bathroom and use it.

I put masking tape on the blades front and back for and throw them in the trash. They are never handled by people again.

I put my old used blades back in container they come in and mark OLD. I use them to trim quilts after quilting and before putting binding on. I was amazed at how long the were sharp. I have a large pill bottle. When too dull to use for anything I throw them in trash

Old machine needles and bent straight pins go into a smaller pill bottle and tossed in the trash.

Our trash hauler doesn't care.

What do you sharpen them with? I’ve sharpened knives with a whetstone and I have a device for scissors, but not rotary blades. Does it work well?

Sally, that is what i do also!!!

use of used blades.
 

I use my old blades for outside projects. They are perfect for cutting plastics, landscrape fabric and fiberglass window screening. Tinker

I also put my old blades in an old pill bottle just for safety. I sharpen my blades with a rotary blade sharpener from Tri-sharp, with limited success. I hear from other quilters that have the electric sharpener that it's not much better. Easypeasy I drilled hole in scrap block of wood to fit my seam ripper in and cut my chained-pieced blocks apart that way, it works really fast and it's cheap.