Below are two quick videos describing how to perform a perfect item jump and a pick-up (AKA Nozu) jump.

In summary: Both a perfect item jump and pick-up jump allow you to perform a paint jump with any item in the game (except for the fan blade). A pick-up jump allows you to take the item with you.

To perform a perfect item jump, the item must be dropped a specific distance away from your character model at the moment you begin a jump. The distance at which you must place the item will vary depending on item type.

To perform a pick-up jump, quickly drop and grab an item while looking straight down, pressing jump at the same moment you re-grab the item.

Both jumps give the same effect as a paint jump, and can be used on the same surfaces. Like paint jumps, they are FPS dependant. A pick-up jump gives less height than a perfect item jump, which in turn gives less height than a paint jump (pick-up jump < perfect item jump < paint jump).