AlessandroAzzolini@G4mma159 Just go to the "Edit Product" page of one of your designs and under the "Customization tab", click "Manually by me" and then fill in the required fields. I hope that now you have understood how to do it. If not, I suggest you to contact the guys at Shapeways here: www.shapeways.com/contact . They are fantastic and very helpful.
AlessandroAzzolini@brickbishop Sure you can! It is possible to add the ring to the cart by clicking the light-blue "Add to cart" button and filling in the size form that appears.
AlessandroAzzolini@aimeemoyer
Thank you very much Aimee!!! No, I think it wouldn't need any design adjustment for a cast metal version. Now metals are available ;)