I've done some checking on patents, fees, etc. associated with fanned fret designs.
Ralph Novak, of Eugene, was granted a patent for the design in 1989, despite its being based upon instruments made as long as 400 years ago. His web site purports to license the design for $75 per instrument, less in quantities of 10 or greater. However, the patent has expired according to Wiki and other sources. One source wrote Novak and got a response acknowledging that the patent had expired.
However, Novak also holds a trade mark for the term "Fanned-Fret", exactly as spelled and capitalized. It appears one could use terms like "fan-fretted", or "fanned-fret", or "fan fret" or "multi-scale" with no infringement. Novak's trademark is non-expiring, as long as he stays current with the fees.
There is a simple to use, free spacing calculator for making a fanned-fret fingerboard at:
http://liutaiomottola.com/formulae/fret ... ocId525252
Here is a Michael Doolin article on cutting a fanned fret fingerboard:
http://www.doolinguitars.com/articles/fannedfret/
Doolin makes it clear that the fingerboard must be tapered to final dimensions before cutting the fret slots (unlike a standard fingerboard, which can be cut before tapering).