Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/8=320
M:9/8
K:C
['D2 d', 'E/F/GE D2 a gfe', 'E/F/GE AFA BGB']  
X:1
L:1/8
Q:1/8=320
M:9/8
K:C
 D2 d cAB c3 | GEC CEC E/F/GE | D2 d ^cAc d3 | AFD DFD E/F/GE :| D2 a gfe c3 | GEC CEC E/F/GE | 
 D2 a gfe d3 | AFD DFD E/F/GE :| AFA BGB c3 | GEC CEC E/F/GE | AFA BGB dcd | AFD DFD E/F/GE :|  