I've been drawing quick-sketch caricatures at parties, fundraisers and corporate events for more than 20 years. They're "quick" in that I spend five or six minutes on each face, which works out to ten to 12 caricatures an hour. People love to gather 'round and comment on their friends' features as they emerge from the page, and I usually have a long line of willing "victims." People have come up to me years later to talk about a sketch of themselves or a relative that's still on display in their homes. (Unlike my political cartoons, the party caricatures are cruelty-free.)
With party caricatures, I prefer to work by the hour rather than charge for individual drawings. They're usually drawn in colored pencils on 8" by 10" double-ply Bristol board. I supply all art supplies and paper; all you need to provide are a table that doesn't wobble, two or three chairs and enough light to see by -- and I'll even bring the table and chairs if you ask me to. My current rate is $100 an hour.
There aren't many drawings in the section because most party caricatures go home with their subjects, but here are two from a 2010 fundraiser for the Lost Colony outdoor drama. The theme of that event was "Under the Sea," which explains the trident and mermaid tail, but I can put your guests in any setting you wish or just draw their smiling faces.

