You can use a circular saw with a carbide blade. Use a straight edge to guide the saw and cut slowly so you dont chip it out. If you have one a triple chip blade designed to cut soft metal like aluminum or brass is ideal. Use an orbital sander to remove saw marks with 100, 150, and 220 grit sandpaper followed by a red Scotch-Bright pad.

I'll get the blade & give it a shot. C.