A custom generator that removes specific blocks (for example, stone) from the default vanilla generator. Also, I made a datapack that disables oceans and rivers because water was affecting FPS. It also has /customblockgenerator pregen <start/stop> command to pre-generate chunks using Paper's asynchronous chunk generation.

Timeframe: 1 day

Client's review: 5/5, "Explained really well to me and the plugin works perfectly :)"