I love the series of posts that Karen put together over at The Art of Doing Stuff. In need of a bird bath and unwilling to justify the insane expense for crappy/ugly design (a feeling I often share), she crafted her own: you can check out the ridiculously simple ‘how to’ over at her site. There are three versions…the free, the $6 variety and covet-able $20 version.
Your ideas are quite artsy looking, but while you are at it, why not design a bath that birds would actually use? The vessel would need to be very shallow–no more than 2″– and very gradually sloping to the deepest part. Also, any surface that is slick would not allow the birds to grip with their toes and stand securely. So the inner surface, at least, needs texture.
So, consider these factors IF you really care about the birds’ needs.
As the person who designed and made these “artsy” birdbaths, I can assure you they’re fine. I’ve chosen to leave the first (Ikea candle plate) version in my yard all year long and the birds are always in it. No broken birds necks yet as far as I can tell.