Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/4
M:6/4
K:D
['D D2 E F2 G A2 B', 'e c A'  
X:1
L:1/4
M:6/4
K:D
 D | D2 E F2 G | A2 B c3/2 B/ A | B c d e c A | A (d2 d2) D | D2 E F2 G | A2 B c3/2 B/ A | 
 B c d e c A | A (d2 d2) :: (c/d/) | e c A d3/2 e/ f | B3 g3 | f e d e3/2 d/ e | (A3 A2) f | 
 g2 f e2 d | c3/2 d/ e A2 A | B3/2 c/ d e c A | A (d2 d2) :|  