Adds more recipes to Foundries: engines, steam turbines, pumpjacks, etc. Allows casting engine units and space platforms directly from metal.
Small changes concerning balance, gameplay, or graphics.
Furnaces, assembling machines, production chains.
I think that single-cylinder engines and inserter parts from Krastorio 2 Spaced Out, and, probably, all items from Fluid Must Flow would be fitting to be craftable in the foundry.