Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:2/2
K:D
['(3gfe fd edBd', 'BAFA DFAD FAdf (3gfe fd edBd f2']  
X:1
L:1/8
M:2/2
K:D
 D2 (3FED FAAf | (3gfe fd edBd | A2 FA ABdf | (3gfe fd edBd | D2 (3FED FAAf | (3gfe fd edBd | 
 A2 FA ABde |1 f2 eg fd d2 :|2 f2 eg fdde |: f2 df e3 c | dcdA BAFA | DFAD FAdf | (3gfe fd edBd | 
 f2 df e2 ce | dcdA BAFA | DFAB defg |1 afeg fdde :|2 afeg fd d2 ||  