I made a post last summer after vacation about dropping my Canon 70-300.  Changing the lens at the Custer battlefield and dropped it on asphalt.  Wouldn't attach to the camera after that.  Is there any reason to hang on to it or just pitch it?

I had hoped to get a "L" lens by now, maybe next year.  The new 70-300 I got at KEH looks brand new!

Maybe do some optics experiments with it?

That's what I'd do if I were in your position.

For example, mating it up with a USB webcam.

Or possibly seeing if it can be used as a macro lens by reversing it (with a special thread adapter) - although I'm unsure of whether or not that will be possible or practical with that zoom lens.

Thanks

Take it apart for the cool optics or sell it for parts.

A friend told me about KEH and I got an old 300 F2.8 AF-S Nikkor lens from them. He said they graded conservatively
and he was correct! Mine looks out of box new except on the bottom of the tripod foot where it has marks of being sat down. it was EX+
It does not look like it was ever mounted on a tripod. It cost less than my 24-70 F2.8 zoom. He warned me their packaging
was not great and that was true...pretty bogus looking and moving in the box. But it arrived in perfect order.

KEH rocks.

The packaging on mine was bomb proof.