Expandable TNT cobblestone farm

A small cobblestone farm built around a TNT duper. A lava and water generator keeps making cobblestone, the duped TNT blows it up, and a water stream carries the drops to the chests. It makes cobblestone, not stone, whatever the title says. It runs on TNT duping, which Paper and Spigot servers block unless the owner changes a setting, so it suits single player and servers that allow it.

• Keep the chunk loaded while it runs. In an unloaded chunk the TNT explodes in the air and blows up the roof, so switch the farm off before you leave. 33 likes.
• TNT that does not dupe or light is the most common failure. Rewatch the redstone part and check that every observer faces the right way. Many builders report it, up to 18 likes.
• On a Paper or Spigot server TNT duping is off until the server owner enables it in the settings. The creator's own comment.
• For stone instead of cobblestone, feed the chests into an auto smelter or furnaces. Several builders suggest it, 9 likes.