Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/8=160
M:6/8
K:D
['EFE EFA B2 A', 'dcB efe efg fdB']  
X:1
L:1/8
Q:1/8=160
M:6/8
K:D
"^E dorian" EFE EFA | B2 A Bcd | DED FDF | ABA AGF | EFE EFA | B2 A B2 c | dcd AFD | EFE E3 :| 
 d2 d dcB | efe efg | fdB Bcd | ABG FED | ded dcB | efe efg | fdB AFD | EFE E3 :|  