Slight warning: I have not tested the ban hammer much, so if it bans you from your server when you use it, I'm very sorry!

This requires a -dev version of Minetest from at least the 15th May. (When register_on_punchplayer was added)
Github link: https://github.com/Amaz1/banhammer.git
Download: https://github.com/Amaz1/banhammer/archive/master.zip
Depends: Nothing!
License: WTFPL code and banhammer texture, CC BY-SA 3.0 kick pick texture, based off BlockMen's pick texture.