Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/16
M:2/4
K:Amix
['AAAA B2d2', 'B2B2A2A2 e2 AAA2 A2Bd edcB A4 BBAB', 'f2ef e2dB']  
X:1
L:1/16
M:2/4
K:Amix
 e2 | AAAA B2d2 | e2A2 BBAB | G4 G2AB | d2G2 BBAG | AAAA B2d2 | e2g2 BBAG | A2Bd e2dB | B2B2A2A2 :: 
 e2 | AAA2 A2Bd | edcB A4 | BBAB GABc | dcBA GGed | c2Bc d2cd | e2g2 BBAG | BBg2 e2dB | BBA2A2 :: 
 Bd | e4 e2de | f2ef e2dB | d4 dcde | f2ef e2dB | e4 e2de | f2ef e2dB | g2ea e2dB | B2B2<A2A2 :|  