Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:3/4=40
M:3/8
K:G
['(gf)G (ed)G', '(cB)G (ed)G', 'dba gBd', 'g2 B cAf gbB cAf g2 d']  
X:1
L:1/8
Q:3/4=40
M:3/8
K:G
 G | (gf)G | (ed)G | (cA)G | (ed)G | (gf)G | (ed)G | (dc)A | G2 :: B | (cB)G | (ed)G | (cB)G | 
 (ed)G | (gf)G | (ed)G | (dc)A | G2 :: d | dba | gBd | cAf | gbd | dba | gBd | c(Af) | g2 :: B | 
 cAf | gbB | cAf | g2 d | dba | gBd | cAf | g2 :|  