A few years ago, one of the casters of a revolving chair broke into pieces. Regarding the chair, a replacement caster was placed and still remains in use. With regard to the broken caster, surely most people would have thrown it in the trash, and that's the end of the story. But for those like me, who like to reuse materials, it was an opportunity to transform waste into something useful....and to have fun.
With the stem of the caster I made a center-finding pin on the Unimat lathe:
This is a commercial center finding pin: Center-Finding Pin - Lee Valley Tools
This tool is useful for accurately aligning the center point marks on the workpiece with the center point of the drill press. You only have to grasp the pin in the chuck, align the pin with the mark, clamp the workpiece, replace the pin by the drill bit, and you are ready to do a precision work.
This center finding pins would also be useful on the mill, lathe and router.
With the wheels I made a pair of threaded knobs, gluing the bolt with epoxy resin.