"This is a basic multipurpose arena built for the Eye of Cthulhu, King Slime, and other Events. While basic, the main thing is that it is functional (Tested with King Slime). Later on, it will recieve upgrades (notably when I get a good supply of Honey) and it will eventually become the very arena I fight the Mechanical Bosses, Golem after getting the Picksaw, and even Moon Lord himself.

If you want to know, each floor of the arena is 21 blocks apart from eachother. the solid bits of the second and third floors of the platforms are seven blocks long on the top and five blocks long on the bottom. The Platforms themselves are separated so that their is a solid platform (or pillar) every 32 platforms placed.

As for the amount of "pillars" needed, I like to keep an odd number because I like putting my banners in the middle, so I would go with three pillars in Standard Mode, and five (as seen in the picture) in expert mode due to more space being required to fight the Eye of Cthulhu. You "could" do it with a smaller arena in Expert, but it is a lot easier if you have a longer arena.

but for now, this is the general look of the structure and some basic dimentions to make it easy to build. If you have any questions, comment on this and I will get to them eventually (because I am very OCD about notifications, I will see the post) If you have a private question, PM me if I am on."