Formulate a musical piece by utilizing the specified motif and alphabet-based structure.
X:1
L:1/8
Q:1/8=280
M:2/4
K:D
['Ad fa', 'aa fd']  
X:1
L:1/8
Q:1/8=280
M:2/4
K:D
 Ad fa | Ad fa | gB cB | gB cB | Ad fa | Ad fa | gB cB/c/ | ed d2 :| aa fd | aa fd | gB cB | 
 gB cB | aa/a/ fd | aa/a/ fd | gB cB/c/ | ed d2 :|  