Welderberg is an odd hairy creature in the third dimension of Flopside in Super Paper Mario.
He seems to be able to flip dimensions, and make gateways through them, and is also skilled at making warp pipes in a few seconds. Welderberg can make a pipe from Flipside to Flopside for 300 coins, a pipe fromFlopside Tower to the Flopside Pit of 100 Trials for 100 coins, and a pipe from Flipside Tower to the Flipside Pit of 100 Trials for also 100 coins. After you have all three pipes, it is unknown where Welderberg goes.