Full size, and a fraction of the cost. OldSchoolStructure built a full sized air hockey table entirely from scrap, only purchasing premade pucks and mallets. The frame is whitewood, the 'ice' MDF, and the air source? A leaf blower.
"An attached 3D drawing of the project might help you understand this project. You can download it in the Images and Files menu below. In order to view this drawing you need the free application Google Sketchup Viewer. Once you've downloaded the file, change the file type from .tmp to .skp (simply by changing the name)."