Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:3/4
K:G
['A2 z']  
X:1
L:1/8
M:3/4
K:G
 D | GFGG A2 | FE F2 z D | GF G2 B2 | BA A2 z G | AG A2 d2 | cB A2 z A/A/ | G/G/F G2 A2 | DF G2 z |]  