[en] Advances made in recent years make it possible--and more importantly, practical--to perform photom and electron transport in complex three-dimensional geometries. The purpose of the work given is to acquaint the user community--experimenters and applied scientists--with the kind of calculational information which can be generated with present codes and computers. The central discussion involves the solution of coupled photon-electron problems using Monte Carlo methods in general, and the code SANDYL in particular. The examples presented are results of such calculations obtained with this code. The emphasis on SANDYL is not intended to imply superiority over other codes, and it should be viewed as representative of currently available codes