A layered BSDF mod­el de­scribes the dir­ec­tion­al re­flect­ance prop­er­ties of a ma­ter­i­al whose in­tern­al struc­ture con­sists of a stack of scat­ter­ing and/or ab­sorb­ing lay­ers sep­ar­ated by smooth or rough in­ter­faces. The bot­tom of the stack could be an opaque in­ter­face (such as a met­al) or a trans­par­ent one. Such struc­tur­al de­com­pos­i­tions in­to lay­ers and in­ter­faces dra­mat­ic­ally en­large the size of the “lan­guage” that is avail­able to de­scribe ma­ter­i­als, and for this reas­on they have been the fo­cus of con­sid­er­able in­terest in com­puter graph­ics in the last years. 

In this doc­u­ment, we present lay­er­lab, a Py­thon-based tool­box for com­pu­ta­tions in­volving layered ma­ter­i­als that im­ple­ments a mod­el re­cently pro­posed by Jakob et al. The pur­pose of this doc­u­ment is to serve both as a gentle in­tro­duc­tion in­to the un­der­ly­ing the­ory and as a hands-on tu­tori­al on solv­ing prac­tic­al lay­er­ing prob­lems with this tool.