Detailed 'ground up' magic item creation rules in Age of Treason
For large objects such as a ship, I think there is room for an extension of the crafting system.
Simple level:
One key high end craft skill - Shipbuilding - supported by a labour force with one key craft skill (carpentry)
Craft (shipbuilding) needs modifying according to the skill level of the labour available (e.g. if the labour force is a bunch of people who average 50-75%, no bonus or penalty, otherwise, roll is modified)
However even here there is ropes, rigging, sails etc that all needd differnt skills to apply to the most simple vessels. You could of course make the rigging and sails a separate craft procedure.
Complex Level:
Art (Architecture) to build a temple? - also requires craft skills of masons, metalworkers, builders, wranglers, labour, etc - Or is it that a master mason also needs an architect. Basically any large project where multiple craft skills are required, and multiple levels of expertise. how does that work?
I was reading MRQ1 Pirates the other day (it's very good by the way). Occurred to me that this could be done similarly to the rules for a ship's crew given there. You have some key roles where the skills of an individual PC or NPC can make a big difference, then you have further modifications according to the general level of the crew.