Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:D
['A2 FD E2 DE', 'dfed B2']  
X:1
L:1/8
M:4/4
K:D
 B2 GB A2 FD | E2 DE FA A2 | BcdB A2 FD | E2 DE FD D2 | BAGB AGFD | E2 ED EFGA | BcdB A2 FD | 
 E2 DE FD D2 || dfed B2 A2 | dfed cd e2 | dfed B2 AF | E2 DE FD D2 | dfed B2 A2 | dfed cd e2 | 
 fdec dBAF | E2 DE FD D2 ||  