Hotline Miami 2's map editor is finally out. Sort of. It's currently available in beta, and you can access it instantly by simply downloading the game's latest update on Steam.
Though it's listed as a 'beta', Dennaton has released the map editor for players to play around with and is fully functional. The editor allows you to create maps similar to the ones used in the game itself.
Unfortunately, because it's still in beta, there's no Steam Workshop support so you won't be able to easily share your creations or download anyone else's maps. For now, you'll need to share them the old fashioned way, by copying files and sending them to your friends.