Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:Dmix
['FDAD FDAB', 'EDD E FDFA d3 B cBcG EFGE']  
X:1
L:1/8
M:4/4
K:Dmix
 E | FDAD FDAB | cBcG EFGE | FDAD FDAB | cBcG EDD :| E | FDFA d3 B | cBcG EFGE | FDFA d2 ed | 
 cAGE EDD :|  