Surriptitious Loop Building

[Paulzric@aol.com]

Question: since most loop building consists of a real-time operator, 
hands-free, what are some options for building loops without the audience 
having to track the entire process? That is, at some point, I'd suspect, 
it would be nice to hit them with a fully developed loop that is 
consistent with the theme played at the time, but one that wasn't observed 
(or whatever word...witnessed, experienced) during its development?

Any ideas, routing and gear and etc., would be appreciated. The lower the 
budget, the better, but not necessary.