I have repaired and played brass musical instruments and am considering building a prototype for a trumpet using Shapeways metals materials. I have a couple questions on best practices and process. 1) Is it best to not have nested parts, such as the valve pistons, which could be part of the model or could be separated out as 3 individual parts? (Value Springs, too) 2) How best to handle threaded items, such as screw caps or items that thread onto a second part? Can they be done as part of the same model or should these threaded parts be unique pieces? 3) With my model, at least one tube part needs to be inserted and slide freely inside of a second tube for the tuning mechanism. This is how tuning is done on a trumpet or trombone. Are there any tricks with the process to make this happen best? Should the tuning slide tube part be a separate piece from the body of the horn? I have always thought casting would be an interesting way to make a horn, but the weight was the killer. The DMLS process is very promising for new trumpet models. New options for shaping the horn seem very possible.