We print on whatever was available. If 4x or larger are needed, we just have to have them in stock to print on. 4x or larger tends to have a noticeable jump in pricing on the shirts themselves, and so we tended in the past to print those on specific request.
I do know we still have the screens for the 3 color “Caution: Makers at Work” caution stripe design so that design is also available to be printed.
Astrud and I can come in to do printing with enough advance notice (we’re pretty busy restocking for our craft shows that are kicking back into gear). We’re not comfortable doing it as a class, but can do a run to get some stock available if PR (or whatever committee is appropriate) is available with a credit card to go buy the shirts at our local preferred supplier.