Old-fashioned wooden tennis rackets (none of your modern ultra-light graphite models) have had the strings removed and replaced by a mirror. As they are made from vintage materials, the design of each racket will vary. Quirky certainly, but a nice talking point for your home if you are of a sporty persuasion.
The Vintage Racket Mirror costs £50 from the Velvet Ribbon website. If squash or badminton is more your game, then you can buy one of those fashioned into a mirror on the Velvet Ribbon shop on Not on the High Street.