 A large number of luthiers worldwide have incorporated Smallman's design innovations into their own guitars.The terms double-top, sandwich-top, and composite-top all refer to a relatively new way to construct the soundboard of a guitar, developed by Matthias Dammann in Germany in the late 1980s.Other luthiers such as Robert Ruck, Fritz Mueller, Jim Redgate, Michel Bruck, Boguslaw Teryks and Gernot Wagner have since adopted the method.