Minecraft – How to equip armor

It is NOT a portal. Using a pattern of gold and cobblestone blocks, the reactor builds a 17x17x17 nether cube in which you are trapped while the thing spews out all kinds of resources like ingots, beds, glow stones, and zombie pigmen. The cube then slightly deteriorates and the reaction is over. The core can be used as many times as desired.

The only people who can join your world are people on the same network.

In the options, under Multiplayer, uncheck "Server visible by default". This will make any new worlds you make unjoinable.

Then, enter your world. Pause the game, and click the bottom button such that it says "Server is invisible". Ta-da!