Develop a musical piece employing the provided motif and an alphabet-based structure.
X:1
L:1/8
Q:1/8=160
M:6/8
K:D
['AFA AFA', 'def afa', 'fef fef']  
X:1
L:1/8
Q:1/8=160
M:6/8
K:D
 d/B/ | AFA AFA | BGB BdB | AFA Ade | fed BdB |"^5" AFA AFA | BAB BAB | def afe | fdB B2 :| A | 
"^9" def afa | baf afe | def afe | fdB BAB |"^13" def afa | bag agf | gfg fef | dBB B2 :| A | 
"^17" def fef | fef fef | def fef | edB BAB |"^21" def fef | fef fef | baf fef | dBB B2 :|  