If you look at older documents the \mathbb characters appear different. For example they are sans serif. I don't know how I can use that set of characters instead of the current default.
If you are not sure what version I am talking about load the package fourier and then use \mathbb{C} for example to see the difference. No other package beside fourier does that and I want to know how to do it with other packages.

\mathbbfont from thefourierpackage but without changing the rest of the fonts? – Juan A. Navarro Aug 16 '10 at 9:06fourier. – Caramdir Aug 16 '10 at 9:26fourier\mathbbfont looks like: caramdir.at/uploads/tex.SE/fourier-mathbb.png – Caramdir Aug 16 '10 at 9:29