Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:6/8
K:A
['aec A2 B cAB ABA', 'Bgg Aff Aff efg gfe']  
X:1
L:1/8
M:6/8
K:A
 aec A2 B | cAB ABA | aec ABc | Bcd e/f/ge | aec A2 B | cAB ABA | agf gfe |1 f3 f2 g :|2 f3 f2 e || 
 caa caa | Bgg Bgg | Aff Aff | efg gfe | caa caa | Bgg Bgg | fga gfe | f3 f2 e | caa caa | 
 Bgg Bgg | Aff Aff | efg gfe | aec A2 B | cAB ABA | agf gfe | f3 f2 g :| a3 ||  