Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:C
['F/ |O E>FGA G>E E>c (E/F/G) (Gc)', '(3efg (3fga']  
X:1
L:1/8
M:4/4
K:C
 F/ |O E>FGA G>E E>c | (E/F/G) (Gc) E>e Td2 | E>FG>A G>AG<F | F>D B,>G, .B,/.C/.D F2 :| f | 
 e>c e/f/g{f} eccf | e>cTcf (3efg (3fga | ec (e/f/g){f} e>cce | f>dBG (B/c/d) Tf2 | 
 ec .e/.f/.g{f} eccf |{f} e>ccf (3efg (3fga | (3gfe (3dcB (3cBA (3GFE | TFDB,G, .B,/.C/.D TF2 ||  