The Old Smithy [Vanilla Small Iron farm with crafter and composter]

"The Old Smithy" is not simply a nice building for your village. It is not even a simple farm.

We do both things here.

It is a building that produces iron and poppies and you will have them sorted out nicely in a couple of chests with the option to auto compost the poppies if you do not need the flovers for decoration or dyes.
The golem killing trap it is high enough that there is no need to make the lowest floor and the sourrounding area spawn-proof, but just the floors above.
I built in a 24x18 area, the building itself is 17x11x22, it has a basament, ground floor with villagers to trade with, first floor with item sorter room and balcony, second floor with villager room and balcony, third floor is the tower with the golem killing zone.

Everything is fully accessible, you can check the redstone work and do maintenence easly, even in the golem spawing zone.

Just mind the moss and carpet, if those are broken the golems can spawn outside their chamber.