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
['AD D2', 'D2 ADcD BDAD cDEc dcAG cdec dA']  
X:1
L:1/8
M:4/4
K:Dmix
|: AD D2 ADEF | GcAG EFGE | AD D2 cDBD | AcGE c2 Bc | AD D2 AGEF | G3 c d2 cd | ecdB cAGE | 
 AcGE ED D2 :: ADcD BDAD | cDEc dcAG | cdec dA A2 | GEGc A3 e | eA A2 dcAG | cEAG EAGE | 
 ecdB cAGE | AcGE ED D2 :|  