Blueprints For Truck Subwoofer In The Planet Mechanics Episode "Tree Powered Car", Where Did They Find The Blueprints?

In the Planet Mechanics episode "Tree powered car", where did they find the blueprints? - blueprints for truck subwoofer

They built a system for the gasification of wood into a truck on the wood chips are only just beginning. They said that the plans for a child in Sweden I (think). Should they pay for the planes, and if so, how? Does anyone know where the plans (available and no plans for FEMA, which is specifically for the mechanical world together. ") So, I know, internet projects, so if not please respond to this question with" They were from the Internet. "