Draw a product structure tree for the patio planter using the BOM below. If there are plans to make eight patio planters, how many bolt and nut sets will be needed?

Patio Planter

* Planter box assembly

** Base assembly (1)

*** Base (1)

*** Rolling casters (4)

*** Bolt and nut set (4)

** Side assembly

*** Side panels (4)

*** Corner braces (8)

** Bolt and nut sets (4)

* Top (1)

* Bolt and nut sets (4)