Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/4=144
M:2/4
K:Amin
['', 'G cc cc c d2 c B2']  
X:1
L:1/8
Q:1/4=144
M:2/4
K:Amin
 G |: cc cc | c d2 c | B2 AB | c z2 G :|  