Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:A
['A2 cA FADF EGBd dcBA fAaA ecAc', 'A3 d cBcd eaga gfed cBAG FEFG']  
X:1
L:1/8
M:4/4
K:A
 E | A2 cA FADF | EGBd dcBA | fAaA ecAc | FGAB AGFE | A2 cA FADF | EGBd dcBA | fAaA ecAc | 
 EAGB A3 :: d | cBcd eaga | gfed cBAG | FEFG Acec | BcBA AGFE | A2 cA FADF | EGBd dcBA | 
 fAaA ecAc | EAGB A3 :|  