Subject: how do the make catalytic convertor

I saw a piece of a catalytic convertor and it lookes like a many tiny 
tubes that sticked together, (something that resamble a beehive but its 
gray and the holes are smaller) and I was wondering how do they 
manufacture thise things?, are the drilling the holse or maybe they have a 
vary sophisticated mold? and if the have a mold how exactly is look like?

Re: how do the make catalytic convertor