Make one. Go to a craft's store and get one of those 'Christmas tree ornament' resin molds and some clear polyester casting resin. This craft was HUGE in the late 60s and I still think it is around. Follow the directions and cast a shallow clear layer in the bottom, maybe 1/4 full. When this hardens, slip a picture into the mold so it lays on the clear plug and cast a very thin coat of clear resin that encapsolates the picture and let it harden. Then fill the mold with clear or colored resin to the top. When hard, break off the glass mold and clean up the ball. Drill the base to accept a threaded metal insert, epoxy it in and you are done!