The Cottage (2008)
The psycho killer is modelled after Leatherface, including his backstory and making human masks.
The farmer uses a pick-axe to kill at least one character.
The farmer uses a shovel to cut half of a characters head off, the same happened in Day of the Dead with a zombie on the receiving end of a shovel.
The skull and spine removal scene is similar to a sequence in Predator.