Blisters, ouch yes...they do nip a bit! Not as bad as the 2"x1"x0.5" monsters I used on my wind turbine though!

Yep, I've been using some platters for coasters too! Seems a shame to melt the platters but I wonder if they're a special grade of aluminium or anything?

I'm intending to make a generator and probably a brushless motor with the hard disk magnets when I've got enough.

You want them magnets?
Yes please! I will of course cover the postage for you, if that's enough?