for the metal grill, i just use heavy duty scissors to cut. for the front cover, i draw a line then first use a blade to make the longkang first, the i use a mini saw to cut slowly.
for the curvy or hard to saw area, i just use screw driver n hammer to keep making holes. dun worry about the finishing because later u can use sandpaper to smoothen out the surface.
but one think to remember is to leave space for glue to apply later. understand kah? hehe