Have a surplus harddisk (two, actually), something that still turns but has too many errors or is too small?

Have a surplus harddisk (two, actually), something that still turns but has too many errors or is too small? How about trying this?


http://hackaday.com/2013/12/12/hdd-driven-table-tennis-robot
http://www.youtube.com/watch?v=goTApke6FzQ