Instructions
Complete the golden spatula tasks in the introductory stage, Downtown Bikini Bottom, Jellyfish Fields and Goo Lagoon.
Speak with Mrs. Puff upon entering Rock Bottom, and then continue along this road to the two rickety bridges. Jump across both bridges, and then defeat the Sleepy-time Robot in front of you.
Continue onto the metal platform behind the robot, and then walk left along the side of the building until you come to a switch. Activate the switch with the Thunder Tikis, which will drop the gate guarding the Duplicatotron 1000 over the metal platform.
Walk back to the metal platform and destroy the Duplicatotron. Activate the switch this reveals, which reveals a second switch, and collect the Spongeball power up. Within 20 seconds, roll to the end of the walkway and activate the second switch.
Flip the switch that appears in front of you. This will bring up a platform -- use the Spongeball to roll along it. Do this within six seconds, before the platform disappears.
Move to the canon on the walkway and destroy it, and then walk back to the toothbrushes on the wall. Climb up the wall here.
Switch to Sandy when you reach the rooftop. Swing between the rooftops until you reach the one with the trampoline. Continue forward between the rooftops to reach the museum.