The ESK package allows to encapsulate Sketch files in LaTeX sources. This is very useful for keeping illustrations in sync with the text. It also frees the user from inventing descriptive names for new files that fit into the confines of file system conventions. Sketch is a 3D scene description language by Eugene K. Ressler and can generate TikZ and PSTricks code. ESK behaves in a similar fashion to EMP (which encapsulates Metapost files), and was in fact developed from it.