The Kaboomerang is one of the unlockable boomerangs which require golden cogs to obtain. Each level in Ty contains 10 golden cogs and in order to unlock this rang you will need a total of 75. You will need to take them to Julius' lab in the hub world, Rainbow Cliffs.
This rang:
NOTE: Obtaining the rang does not use up the golden cogs, you just need to obtain the required amount.