War-Machine MkIII Aluminum armor WIP

[War-Machine]

Ok folks i'm going to need some input from ya. This is a 1 1/2 inch diameter 6061 aluminum. Now the cardboard piece next to it is a tip of a thumb as a reference. Now i thought that i would use a drill press to begin drilling the cavity. The thumb however is not a perfect circle so i was thinking that i would use a dremel to bore out the shape using a carbide burr. Once that is done, i would then form the outer diameter to the desired shape. So i'm asking you the pro's, does this sound viable or do you have a better idea? Thanx in advance...GM