David P James
I agree, I think it's a good idea as well. I too just end up churning out artillery in a few colonies. I think making cannons as a good will go a long way to addressing the asinine hack of artillery price inflation in Europe. That hack to me has all the hallmarks of "we know we've got a gameplay problem but we can't think of a good way to deal with it, so we'll make this hack instead". If the cannon good in Europe is subject to the same price variations of products like furs and rum, then we'll also get our artillery price inflation, but in a saner way. If the price ber cannon and the number of cannon to fit out a colonist is set properly, then the price will roughly match that of artillery.
It could be set up to require tools to produce cannons, and possibly at some rate like 5 or 6 tools to a cannon. It's either that or direct from ore. I don't think there's a way to have a lumber requirement as well though (for the wheels and carriage associated with artillery, unless cannons are a requirement to build artillery - but then you're no longer equipping colonists with cannons).
I also agree that warships could require cannon to build as well - and I like the idea of adding cloth to the shipbuilding requirements (at this point they're needing lumber, tools, cannon and cloth...).
Adding cannons as a good is relatively straight forward, and adding them as a requirement for ships not too difficult either. Equipping colonists shouldn't be too difficult either. A new kind of building will be required either to build cannons or to build muskets, but gunsmiths can probably be the expert in both. Where the problems mount is in rewriting the rules for artillery-in-the-open, the REF, etc. etc.