Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:2/4
K:D
['', 'D/D/ D>F FG G2 B/c/B/A/ B>c cd', 'e2 (e>f) (ec) d2 ff/f/ (f>g) (fe)']  
X:1
L:1/8
M:2/4
K:D
 D/D/ |: D>F FG | G2 B/c/B/A/ | B>c cd |1 d3 D/D/ :|2 d3 d/d/ |]: f2 f2 | (f>g) (fe) | c2 e2 | 
 (e>f) (ec) | d2 ff/f/ | (f>g) (fe) | c2 e2 | GB B/c/B/A/ | B>c cd |1 d3 d/d/ :|2 d3 z |]  