Sentence 1: Sam needed a new desk. 
 Sentence 3: He thought the process of building a desk was fun 
 Sentence 4:  So he began building other pieces of furniture too 
 Sentence 5:  Eventually, Sam became a skilled builder 
 Option 1: But he wanted to save money by building one himself. 
 Option 2: Sam saved money as his brother built a custom desk for him.