unfortunately, i stole my metric calipers from work and left them at home... but using some english ones i measured a piece of aluminum can and found it to be .004" thick... multiply that by 25.4 and you get 0.1016 mm. i.e. a 12 oz aluminum can is too thin, unless you wrapped it around twice. a smaller can, such as a redbull can, MAY be thicker... but i doubt it's going to be the nearly .0078" thick you'll need.

either way this is really putting form before function, which sucks, but that does seem to be the theme of this forum, so RIGHT ON!... or something.

It's all AL anyway shim and post. But true in any case you ought to remove a seat post at least twice a year and put it back in just to be sure you have not welded it shut.