Build Club was an underground organization in Sky City.
Build Club was created by Milo following his arrest for accidentally dropping the dirt block into the void. The club was located behind the wall in a small building. According to laws of Sky City, unauthorized building or crafting was banned. There were at least ten people in this club. It was presumably destroyed after an attack.
The club was made out of cobblestone, oak planks, and wool. There were multiple crafting tables, paintings, and item frames.