Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/8=180
M:4/4
K:G
['DGBG dGBG cBcd efga bg g2', 'bg g2 agef gedB AGEG DB, B,2']  
X:1
L:1/8
Q:1/8=180
M:4/4
K:G
 E | DGBG dGBG | cBcd efga | bg g2 agef | gedB AGEG | DGBG dGBG | cBcd efga | bg g2 ageg | 
 dBAB G3 :| g/a/ | bg g2 agef | gedB AGEG | DB, B,2 DEGA | Bdgb ageg | bg g2 agef | gedB AGEG | 
 DB, B,2 DEGA | dBAB G3 :|  