On lush planets, there will be a miner outside the core fragment mines. They give a quest which instructs the player to obtain a Molten Core via the Distress Beacon crafting recipe at the Inventor's Table.

To use the Distress Beacon, place it on the surface of a planet and remove any background blocks that are behind it, then interact with the beacon to summon a boss (he will be stronger if you summon him on a planet with a higher Threat Level), which drops Molten Cores when killed.

Use a Molten Core at an Inventor's Table to craft a Steelworks Upgrade, which unlocks the Steel Bar recipes for the Industrial Furnace (upgraded furnace) when used. To use it, fire it like you would a gun, to place a block, to swing a sword, etc.

At the outpost, speak to Dr. Akaggy (the penguin mech scientist) after unlocking the modular mech to get a quest which instructs the player to obtain a Processor via crafting an Inactive Robot at an Iron Tool Table.

Accepting this quest automatically unlocks the recipes for various robot parts: Robot Legs, Robot Chest, Robot Arms, Robot Head, and Empty Robot Head. Craft all of these items at an Iron Tool Table.

To obtain the required Artificial Brain for the Robot Head, craft a Brain Extractor at an anvil and kill monsters with it. Only some monsters are capable of dropping brains (they will turn pink when shot), and they will either drop an Inferior Brain or a Superior Brain, the former of which can be crafted into the latter.

Once you have a Superior Brain, craft it into an Artificial Brain at an Iron Tool Table. You can craft the Inactive Robot at an Iron Tool Table or an Engineer's Table (upgraded Inventor's Table).

To use the Inactive Robot, place it on the surface of a planet and remove any background blocks that are behind it, then interact with the robot to summon a boss (he will be stronger if you summon him on a planet with a higher Threat Level), which drops Processors when killed. A processor can be used to upgrade an Iron Tool Table into a Robotic Tool Table.

After doing enough quests at the outpost, the human ex-convict at the outpost will offer a quest which instructs the player to obtain an unknown item (Endomorphic Jelly) via crafting a Peanut Butter Trap at an Engineer's Table (upgraded Inventor's Table).

To craft the Peanut Butter Trap, you must acquire a Peanut Butter jar, which is made from butter and other ingredients. The recipes for the jar and butter are available by default. You create them at a cooking station (there's one at the outpost). Once created, bring the jar to an Engineer's Table (upgraded Inventor's Table) and craft a Peanut Butter Trap.

To use the Peanut Butter Trap, place it on the surface of a planet and remove any background blocks that are behind it, then interact with the trap to summon a boss (he will be stronger if you summon him on a planet with a higher Threat Level), which drops Endomorphic Jelly when killed.

Endomorphic Jelly can be used at an Engineer's Table (upgraded Inventor's Table) to create a Compounding Upgrade, which unlocks the recipes for scintillium/cerulium/impervium compounds at an Atomic Furnace (upgraded furnace).