Formulate a musical piece by utilizing the specified motif and alphabet-based structure.
X:1
L:1/8
M:6/8
K:Bmin
['', 'f2 B BcB', 'fdB fdB']  
X:1
L:1/8
M:6/8
K:Bmin
 g |: f2 B BcB | e2 A ABA | f2 B BcB | d3 g3 | f2 B BcB | e2 A ABA | Bcd ecA | d3 g3 :: fdB fdB | 
 ecA ecA | fdB fdB | d3 g3 | fdB fdB | ecA ecA | Bcd ecA | d3 g3 :|  