The invention exchange was a regular feature of Joel's tenure as host, in which Joel and his mad scientist tormentors would come up with wacky inventions in a contest with each other. These sketches were a good match for Joel Hodgson, who began his career as a prop comic; indeed, many of the inventions were items originally found in his standup act.

The first few Mike Nelson-hosted episodes also featured invention exchanges, but they were soon phased out to accommodate Michael J. Nelson's less prop-oriented brand of humor.

List of Invention Exchanges