I have a client who wants to have lettering painted on the outside of his 20' x 30' corrogated aluminum building.

It is only going to be one large word "REVERE"

How the heck can I make a pattern this large? Can someone point me in the right direction?

As I said in last post or the other way is to lay your text on a graph and transpose it to a larger graph and draw it in. This is what I did before computers.

the letters will only be 6-8 feet tall
draw pattern in pieces on computer & tape together
if it is a block letter, you could figure it out mechanically as they should be the same width.
maybe make a large coroplast E (because there are 3 of them)
then change the shape on the wall for the R & V
hope this helps.