That's a term I haven't heard for a few years...the pattern makers shop. We had a pattern makers shop at BroomWade, where they made all the wooden patterns to create the sand moulds in the on site foundry. The pattern makers were really skilled carpenters, whose tapes and rulers were calibrated to be slightly bigger than normal. This allowed for the shrinkage of the castings as they cooled and thus ended up more or less the correct size, ready for final machining. Big castings like the crank cases of the big 'V Major' compressors went outside for a year to 'season' before being bought in and put through a huge shot blasting chamber before going to the machine shop.