Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:2/2
K:A
['A2 cA', '(3efg ae aeae fecA']  
X:1
L:1/8
M:2/2
K:A
 A2 cA BAcc | efec BAFG | A2 cA cAff | ecBA A2 A2 | [AA]2 cA cAff | ecec BAFG | A2 cA cAff | 
 ecBc A2 A2 :: (3efg ae aeae | fecA BAFG | A2 ae a2 ab | c' c'2 (b a2) a2 | (3efg ae aeae | 
 fecA BA (3efg | a2 cA cAaf | ec(Bc) A2 A2 :|  