how many tools ?
Size would depend on how many tools will be running at once, If you do it your self labor cost wouldn't matter. I took over as facilities manager at a factory and they had 1/2 copper main lines and the first day I could hear the air screwdrivers slow down when 3 or 4 people were working the same time. I always over size , conduit and plumbing systems, cooling water, Air, etc. you need some reserve capacity, If you have to rent a power threader , or make changes later copper is easier,