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 da af fd dg', 'c>d ee d>e fd']  
X:1
L:1/8
M:2/4
K:D
 d | da af | fd dg | f>d e>c | d2 z d | da af | fd dg | f>a a/g/f/e/ d3 :: d | c>d ee | d>e fd | 
 c>d ee | d>e fd | da af | fd dg |1 f>d e>c | d3 :|2 f>d a>c | d3 ||  