Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:6/8
K:F
['FGF AGF c2 c c2', 'c b2 a gfe fef', 'F2 A3 GFG F2 F FAc c3', 'd2 c']  
X:1
L:1/8
M:6/8
K:F
 FGF AGF | c2 c c2 B | Acf c2 B | B2 A G2 D | FGF AGF | c2 c c2 f | efe dc=B | c3- c2 |] 
 !fermata!g2 c b2 a | gfe fef | g2 c b2 a | gfe fef | dbb caa | Bgg Aff | BAG c2 E | 
 F3"^D.C." F2 |] A3 GFG | F2 F FAc | c3 BAB | A2 A A2 e | f2 e e2 d | d2 c c2 B | ABc cBA | 
 (A3 G2)"^D.C." z |] f3 fd=B | cdc ceg | b3 age | fgf f3 | f2 e d2 c | d2 c B2 A | BAG c2 E | 
 F3"^D.C." F2 |]  