Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:C
['eAA eAA efe edB', 'afa geg']  
X:1
L:1/8
M:4/4
K:C
[M:6/8][K:Amix] .abc e | eAA eAA | efe edB | eAA ege | dBA A2 c/d/ | eAA eAA | efe edB | def gfe | 
 dBA A2 :: a | afa geg | fdf ecA | afa geg | dcB A2 a | afa geg | fdf ecA | def gfe dBA A2 :|  