Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:D
['FDAF d2', 'Tfede fgaf']  
X:1
L:1/8
M:4/4
K:D
 A | FDAF d2 TdA | d2 Tdf eEEA | FDAF d2 dB | cdeg fddA | FDAF d2 TdA | d2 Tdf eEEA | FDAF dABG | 
 FAdg fdd || g | Tfede fgaf | gfed cAeg | Tfede fgaf | ecdB Addg | fdfg fgaf | Tgfed cAeg | 
 fdgb afge | fdec d2 d ||  