This page from Fab Lab: Digital Fabrication Learning Community contains all the files necessary to create a dog scratcher. A pdf document lists the materials needed and provides a short description of the project while two .cdr files can be used with Corel Draw software and a 3D printer to create the item. These materials could be used in a lesson in an introductory engineering or manufacturing course.

This video, from the Natural Resources Conservation Service, looks at the Huls family dairy farm in Montana, which uses a methane digester to provide power to the diary operation and the family home. The video outlines the changes to the farm from the introduction of the digester, and highlights the economic and environmental benefits of its use.