In order to make a shotgun you must have gunpowder BBB, grenade rounds, and
the mixing tool. Mix gunpowder BBB with the grenade rounds to make shotgun
parts. Next, mix the shotgun parts with the mixing tool to make the shotgun.
The three jewels in the clock tower:
When you enter the room in the clock tower with the three statues holding
trays, take the obsidian, crystal, and amber jewels from them. There are
three clocks on the wall besides the two dead bodies. Going from left to
right, place the amber jewel in the first tray, the obsidian jewel in the
middle tray, and the crystal jewel in the third tray. The middle clock will
open and you will get a gold gear. Combine it with the silver gear and place
it in the slot on the third floor.