Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/8
M:6/8
K:D
['BFG BGF', 'd3 dcB'  
X:1
L:1/8
M:6/8
K:D
 BFG BGF | DFG d2 d | BFG BGF | d3 GBG | BFG BGF | DFG d2 d | dcB Gdc |1 B2 c2 d2 :|2 B2 A2 z2 |: 
 G3 B3 | c3 d3 | dcB cAB | A3 AGF | G3 B3 | c3 d3 | dcB cBA |1 =e4 z2 :|2 B4 z2 ||  