It’ll be difficult to make a Max patch if you don’t use any externals. I presume you’re referring to third-party work.
If I were you, I’d have a serious look at the Forum postings on the subject. Just do a search on "convolution" or "convolution reverb." Much of the concensus is that it’s either impossible or vastly unsatisfying, which is the reason that the work currently being done is done by means OTHER than vanilla objects. At the very least, I expect you’ll find good advice contained within the discussions.