Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:G
['dGBG dGBG', 'AGEG D3 B BAGE D2 BG AGEG', 'AGEG gedB G2 (3B^cd gdBd eA A2', 'dggf g3 d', 'AGAB G2 (3BAG dGBG', '']  
X:1
L:1/8
M:4/4
K:G
 dGBG dGBG | dGBG AGEG | dGBG dGBG | GABG AGEG | dGBG dGBG | dGBG AGEG | BddB dedB | AcBG AGEG |: 
 D3 B BAGE | D2 BG AGEG | DBBA B3 G | AcBG AGEG :: gedB G2 (3B^cd | gdBd eA A2 | gedB GABG | 
 ABcd eA A2 :| dggf g3 d | eggd (3efg dB | dggf g3 d | (3efg dB AGAB :: G2 (3BAG dGBG | 
 GB B2 AGAB | G2 (3BAG dGBG | (3efg dB AGAB :| d8 ||  