I didn't make it!
does anyone know if its possible to increase the number of items that const ships and shipyards build and if so how could someone do it?
Not as far as iam aware the max they can have is 13 (0 - 12)
I thought the limit was 14 (0-13). Starbases have a limit of 4, I think.
Yes, 14 is the limit for both Bases and construction ships.
Also, I don't know of a direct way of increasing the limit, but you can create a second ship/station to double the amount of build items.