Time And Relative Dimension In Space. A TARDIS will allow you to travel the Multiverse without spending credits on portals. The first thing you'll need to do, of course, is get a TARDIS. John Smith's TARDIS Emporium, located on Spawn Ranch, sells TARDIS seeds of all kinds; get them now because some rarer console patterns might move elsewhere (or get more expensive) eventually. You'll also need a regular TARDIS key; one of the other merchants in the shop sells them.
Go to anyplace you're allowed to build. Because this will be your TARDIS's default home location, it is advisable to create your TARDIS on your own /lands claim, but it is not required. Place the TARDIS block on the ground, right-click it with your TARDIS key, and step back! You'll see a loading bar at the top of your screen; once it's complete your new TARDIS will begin to materialize! When it finally stays solid, you'll be able to open the door by r-clicking. Once you are inside, be sure to close the door! Other players and some mobs will be able to enter if you forget. Once the door is closed, find the Artron capacitator. It's the wooden button, somewhere on your control panel. Right-click it with the TARDIS key, and your shiny new space box will be ready to start traveling!
Most TARDIS functions will require an additional blueprint; these are for sale in the TARDIS Emporium. Once you have them in hand, put them in your Artron condenser (it's a chest, somewhere in or under your TARDIS control room) and close it. This will permanently unlock that feature for you. To use circuits and disks, you must put them into the Advanced console (it's a block with green circuit boards on it, somewhere in your TARDIS control room. Circuits and disks are only active while in the Advanced console.
Your TARDIS runs on Artron energy. To get more, you can purchase Artron batteries on Spawn Ranch, or you can fill your Artron condenser up with raw materials and extract the energy from them.