Aluminum Extrusion and Edges

Hello everyone, I've been reading the forums for a long time, and this year I'm starting my first build. But I have a question... If your familiar with enclosed cargo trailers, or even a box truck... they use extruded aluminum and edges... many time with running lights. They even have rounded corners. I thought it would be cool, and easier to build the trailer like that, but I cant find ANY information about it, or even who sells the materials like that. Does anyone have any suggestions or web links? Thanks in advance!

