First things first, you need to beat any single mission legitimately. Any mission will work, no matter how far into the game you are. Complete the mission all the way to where the Starite appears for you to collect. However...



Instead, you're going to want to spawn in some sort of tethering item (EX: A rope, chain, etc.) that you can attach to the Starite. Once attached, drag the rope into your Magic Backpack.

Now, anytime you open up a new mission, just drag the rope out of your backpack, and collect the Starite to instantly complete the level!

• Make sure Maxwell is in the very center of the screen. When you spawn the Starite from your Backpack, it will automatically spawn in the center of the screen. If it's put in an area that will cause it to despawn, you will have to restart the mission. There is one mission that I vaguely remember having to complete at least part of it, due to the camera and level being positioned in a way that wouldn't let me collect the Starite, but aside from that, most missions should let you collect it immediately.
  
  
• You can use this for getting "$ Items". These are basically just items in the game that you normally cannot spawn with your notebook, and consist of dev items and mission-specific objects that solely exist in said missions. While these are fun to play around with, be careful, as some items can crash your game.