I have a bunch of used, empty spools.
Mostly black plastic, a couple clear ones.
Various brands.
Other than occasional damage on the edges from Amazon packing them poorly for shipping, all in very good shape.
Most of them do have some sharpie or other pen markings on them, from recording some details on each one.
You could use them to respool other filaments onto, I know some people do that.
These are NOT the "reusable" kind, where they come apart and you put a special refill of filament onto them.
These are one piece.
I'm sure there are plenty of non-printer uses.
Wind up cables for organization
Wind up yarn/rope for storage
Christmas light storage (not for large/long strings, these aren't huge)
I currently have about 30 of them, with more being added every day.
I already have someone who takes my used cardboard spools.
These are free.
Pickup in Bellingham near Home Depot at a pre-determined time.
Delivery within Bellingham or Ferndale is possible if prepaid via Venmo.