I bought some cheap 3mm single flute cutters from Ebay, whilst the cutters themselves are good the initial edge applied to them is a little random, fortunately the single flute cutters are very easy to hand sharpen and and a quick touch-up on a diamond wheel is all they needed to get them cutting cleanly. They're not listed as suitable for Aluminium but I've used one on Brass, Bronze, Aluminium and Titanium and I'm still on the first one of a pack of 10 ;-)

- Nick