First off, you might want to read through the Musical Instrument Design and Construction forum:
Alot of people are building instruments and probably can give you a good answer to your question.
If you can design your product in 2D, 2.5D, or 3D, then you might want to consider CamBam as a product to gen up Gcode from your drawings. I have seen a 3DS file loaded into the product.
Thread: http://www.cnczone.com/forums/showthread.php?t=14963 (CAMBAM - 10Bulls crazy CAD/CAM software project)
CamBam runs in .NET and requires .Net 2 to be installed on your computer to run the software. It is free and works pretty good. Good support
There is also NCPlot. It is $75 and is very good for generating Gcode and working with your drawings.
Website: http://www.ncplot.com/ Go to NCPlot V2 Beta link and download. Product runs good and has good support.