Which of the following are tweaked for use as spacers and blocks?

• hockey pucks
  Some car and truck enthusiasts report saving money by rigging hard plastic objects like hockey pucks, wood piece and skate wheels, though they are prone to wear, breakage and safety issues.
• wood pieces
  Some car and truck enthusiasts report saving money by rigging hard plastic objects like hockey pucks, wood piece and skate wheels, though they are prone to wear, breakage and safety issues.
• skate wheels
  Some car and truck enthusiasts report saving money by rigging hard plastic objects like hockey pucks, wood piece and skate wheels, though they are prone to wear, breakage and safety issues.
• all of the above
  Some car and truck enthusiasts report saving money by rigging hard plastic objects like hockey pucks, wood piece and skate wheels, though they are prone to wear, breakage and safety issues.