For information on Anvil in vanilla Minecraft, see this page.
When a Poké Ball disc, iron disc, aluminum disc, or aluminum ingot has been made, using an anvil while holding the item will place it on the anvil. Then, by hitting the anvil with a hammer, discs will gradually get rounder and aluminum ingots will get flatter. Each item will change appearance three times before it is complete. Once they have been affected three times, using the anvil or continuing to hammer the item will cause the finished product to return to the player's inventory.
- "allowAnvilAutoreloading": Sets whether a finished item on an anvil is automatically replaced with the corresponding unfinished item from the player's inventory (e.g. a finished lid being replaced with a disc), allowing a player to continuously hold left-click to manufacture items.