When I first started jewellery design I experimented with various mathematical surfaces. The classic one is the moebius strip. I had two designs for sale, one with holes and a solid version. My first attempts came out too thin. This is usually the case when designing in CAD because you can zoom into the design on screen and you always feel that it looks larger than it actually is. Now I always have some vernier calipers with me so I can measure tangible objects and then compare the sizes with the dimensions in CAD.