I have made a iron farm in my world and covered it up with a big iron golem head. now, you can guess what the problem is..
iron golems tend to spawn outside the iron golem farm. I have tried some things (slabs/stairs) but i am running out of ideas.
Does anyone have some creative techniques to make it still look natural (swamp like) and stop the golems from spawning?
As I understand it, this is a hollow shall, so why can't you just put some holes around the base to let the golems walk back in and a kill zone under the zombie they can fall into. A few strategically placed holes should not compromise your design.
Make it larger so that the possible spawning area around the farm is empty space. I have a large building around mine to hide it and made sure the walls were outside the spawning area. I think the spawning area around the villagers is 16x16 and 3 blocks above and below.