Prepare the prison keys
With the Hammer, enter the large forge area. Cast an Iron Key using its matching mold, 5 Coal and 8 Scrap Metal. Also cast the separate Key for the large keyhole door leading into the Jaguar hallway.
In that hallway, the door on the right of the Jaguar Door takes the Iron Key. The small chest at the far end of its room contains the Prison Key and Club. You can obtain the Prison Key without opening the three-piece Jaguar Door.
Find the Small Key route
From the main hall’s upper level, take the cave sloping down to the left. Go through the ruins to the small box at the far end for a Small Key.
Return upstairs in the hall, turn left and left again, and use the large wooden plank to cross the gap. Open the Small Key door, descend the spiral stairs and use a Torch to clear the webs to the right. The next prison entrance takes the Prison Key.
Follow the lower prison stairs
Near the stairs where you first entered the prison, look for another staircase continuing farther down. The lower area beyond the door contains the Pickaxe; the archer skeletons above are useful landmarks.
A broken Fix Lever on this route displays Add Iron Rod (0/1) and consumes one Iron Rod when repaired. Keep a rod for that repair, and read each further mechanism’s own prompt before spending more materials.
Once you have the Pickaxe, return to yellow goo piles for Clay.