Short answer: the Boiler Room has 3 standard bundles, which need 9 items in total. Finishing all of them gives you: Minecarts Repaired. The Boiler Room appears after completing two bundles. With Remixed Bundles turned on, some bundles below can be swapped for one of 3 other bundles.
Completing all Boiler Room bundles repairs the Minecarts, allowing the player to fast travel between distant locations.
Blacksmith's Bundle
Bring all 3 items. Reward: Furnace.
| Item | Needed | Season | Where to get it |
|---|---|---|---|
| Copper Bar | 1 | — | Smelting Copper Ore in the Furnace |
| Iron Bar | 1 | — | Smelting Iron Ore in the Furnace, Crafting the "Transmute (Fe)" recipe |
| Gold Bar | 1 | — | Smelting Gold Ore in the Furnace, Crafting the "Transmute (Au)" recipe |
Geologist's Bundle
Bring all 4 items. Reward: 5 Omni Geode.
| Item | Needed | Season | Where to get it |
|---|---|---|---|
| Quartz | 1 | — | Foraging on all floors of The Mines |
| Earth Crystal | 1 | — | Foraging on floors 1-39 of The Mines, Geodes, Omni Geodes, drop from Duggies in the Mines (floors 6-29) |
| Frozen Tear | 1 | — | Foraging on floors 41-79 of The Mines, Frozen Geodes, Omni Geodes, drop from Dust Sprites in the Mines (floors 41-79) |
| Fire Quartz | 1 | — | Foraging on floors 81-119 of The Mines, Magma Geodes, Omni Geodes |
Adventurer's Bundle
Bring any 2 of these 4 items. Reward: Small Magnet Ring.
| Item | Needed | Season | Where to get it |
|---|---|---|---|
| Slime | 99 | — | Dropped by Slimes |
| Bat Wing | 10 | — | Dropped by Bats in The Mines or the Skull Cavern |
| Solar Essence | 1 | — | Dropped by Ghosts, Squid Kids, or Metal Heads in The Mines, dropped by Mummies or Iridium Bats in the Skull Cavern … |
| Void Essence | 1 | — | Dropped by Shadow Brutes or Shadow Shamans in The Mines or Serpents in the Skull Cavern; produced by Void Salmon in Fish Ponds; buy from Krobus |
Remixed bundles in this room
If you chose Remixed Bundles when you started the farm, the game can use these instead of some of the bundles above. Which ones you get is random per save, so check the room in your game.
- Adventurer's Bundle: 99 Slime, 10 Bat Wing, Solar Essence, Void Essence, 10 Bone Fragment (any 2). Reward: Small Magnet Ring.
- Treasure Hunter's Bundle: Amethyst, Aquamarine, Diamond, Emerald, Ruby, Topaz (any 5). Reward: Lucky Lunch.
- Engineer's Bundle: Iridium Ore, Battery Pack, 5 Refined Quartz. Reward: 2 Furnace.