Instructions
Go to the Who Forest, and find the first Slime Shooter BP in the first cabin you see.
Go to the second cabin in the forest, and find three additional BPs inside.
Go to the cabin that is closest to the forest clearing. You will find a fifth BP inside.
Go to the cabin near the unusually large hollow tree. A sixth BP is inside.
Go to the ski lift area and enter the cabin under the ice wall to find a seventh BP.
Find the eighth BP in the green cabin on the cliff. Find the ninth and last BP in the pink cabin, also on the cliff. Once you have all the blueprint pieces, the Slime Shooter will be assembled.