Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:Edor
['B2 df', 'Beeg faec']  
X:1
L:1/8
M:4/4
K:Edor
 B2 df eBBd | AD (3FED FAAF | B2 df eBBc | dBAF B2 E2 :| Beeg faec | defg afed | Beeg faec | 
 dBAF B2 E2 | Beeg faec | defg afed | fb b2 fa af | dBAF B2 E2 ||  