You can make garden spheres out of recycled bowling balls. This would be awesome if you use the tumbled glass stones from the craft store in colors to match your yard! bowling balls are waterproof and frost resistant although I would store in garage for winter not sure how resin would hold up.
DIY Gazing Ball Designs -- What a fantastic recycling or up-cycling project from Penn State Extension. Make a garden gazing ball from a bowling ball! I love it! And, it isn't fragile or breakable like so many of the glass versions. Now, off to find an old bowling ball!