Software packages developed for visualising time-varying timbres, finding parameter settings for modelling acoustic instrument tones, and for synthesising timbres are described. The sndan package, written in C for Unix machines, provides spectrum analysis, pitch tracking, spectrum display, parameter modification, and additive synthesis. Other programs that estimate the best possible parameters for recreating acoustic sounds using techniques such as multiple FM and wavetable synthesis and extended nonlinear/filter synthesis are outlined. Hybrid instruments created by fashioning sounds out of the recombined spectral characteristics of two or more very different tones are also presented.