At Uncle Monty's house you will need to make a pair of Levitating Loafers for Klaus. You will find one of the invention pieces, a pair of boots, outside the shed, above the door, in Uncle Monty's garden. In order to climb up and get the boots, you will need to use the Brilliant Bopper (or the Fruit Flinger) to knock over the water cans that hang from the second floor windows. The spilled water will cause giant flowers to grow. You can then jump on these to get over to the roof and grab the boots.