Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/16
Q:1/4=109
M:4/4
K:G
['d3 z']  
X:1
L:1/16
Q:1/4=109
M:4/4
K:G
 G2.A3d3 z c3B2A2 | G2A2 z2 d3c3B2A3 | GA2 z2 d3 z c2B2A3 | A6 z G2A2 z2 d3 | c3B2ABc d3 z G3 z | 
 A2>F2G3 z G2.A3d3 z | c2>B2ABc2 d3 z G3 | A3F2G3 |]  