There are lots of deviations and people have made some mighty fine looking speakers, both of the exact layout shown in the plans and from some with slight dimensional differences. See the photos in the post called "Pictures of Pi-speakers."A PiAlign'ed JBL 2226 is 2.5ft3 port tuned to 38Hz. The 2226 works pretty well in ported cabinets from 2-5ft3 tuned to 40Hz, so you have a wide range of good choices when building your cabinets.