Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/4=120
M:2/4
K:Amin
['AA AA', 'e2 gg e2 dd dc G2 AA']  
X:1
L:1/8
Q:1/4=120
M:2/4
K:Amin
"Am" A/A/A/A/ AA | AA AA |"Am" A/A/A/A/ AA | AA AA |]:"F" a a2 g |"C" e2 d2 | ee e2 | gg e2 :: 
"Dm" dd dc |"Am" A2"Em" G2 |"Am" AA A2 |"C" cc"Am" A2 :|  