The trick to good foaming is in the generator above the boom (unless you use the GinSan guns which are something like $150 apiece). I've got to make a bunch - I'll post some pictures. I use the Hamel triple foam gun, which is just a triggerless gun, 3/8" in and a 1/4" stub to hold a tip protector and tapped inside 1/8".
Kleen-Rite has some very large 1/8" tips for them. I use the 2540 tip.