Formulate a musical piece by utilizing the specified motif and alphabet-based structure.
X:1
L:1/8
Q:1/8=120
M:6/8
K:D
['A2 d =cBA def gag fed cBA', 'dfa dfa']  
X:1
L:1/8
Q:1/8=120
M:6/8
K:D
 F | A2 d =cBA | def gag | fed cBA | GFG AFD | A2 d =cBA | def gag | fed cBA | Adc d2 :: A | 
 dfa dfa | dfa agf | =ceg ceg | =ceg gfe | fef gfg | aga bag | fed cBA | Adc d2 :|  