Hi Wong. Go with steel for the table top. The attachments sliding around will wear out aluminum quickly, and make a lot of friction as it scratches up. There is no tricky machine work on the table top. I think brass dovetails will work. Brass is easier to machine. My mill/drill chattered some when cutting them in steel. The angle bracket at the bottom could be steel too, or extra heavy thick aluminum. That part needs to be very rigid. Aluminum for the rest should work out. Mr Hall's plans are metric, if you are using inch, round up all the material thicknesses to make the table a bit more "beefy" A little extra stout will help.
I use the grinding table a lot. It is a really big help.
Bob