Formulate a musical piece by utilizing the specified motif and alphabet-based structure.
X:1
L:1/8
M:4/4
K:D
['ABdB ABdf', 'fgaa abaf']  
X:1
L:1/8
M:4/4
K:D
 ABdB ABdf | gfef g2 g2 | ABdB ABdf | gefd B2 A2 | ABdB ABdf | gfef g2 g2 | fgaf bgef | 
 gefd B2 A2 :: fgaa abaf | gfef g2 g2 | fgaa abaf | gefd B2 A2 | fgaa abaf | gfef g2 g2 | 
 fgaf bgef | gefd B2 A2 :|  