david blumberg wrote:

anyone know of a company making a 3 inch or larger pattern bit for a
router?

I've got a 60mm (bush guided, not bearing - from Axminster's yellow
range) and the longest bearing-guided one I've seen is 2"
(commonplace). Look for "kitchen fitters' worktop cutters".

I wouldn't like to use anything longer! -- and I'm using a pretty hefty
router with them.