Most IC engines are mounted on some type of display board or box containing batterys, ignition systems, and other things needed to make it run. So idealy it is a self contained display piece. Of course the fun is in building them! ! ! You can see tons of photos and Cabin Fever's website:
http://www.cabinfeverexpo.com/
Here is a picture of a vaccum engine I took to the Jan. 2003 Cabin Fever Show.