bbm-package: alternative doublestruck (blackboard) math characters

With the bbm package (\usepackage{bbm}) it is possible to add symbols for several standard sets. Usage : \mathbbm{N} in mathmode gives $\mathbbm{N}$. Some more examples:

$\mathbbm{N}$	\mathbbm{N}	$\mathbbm{Z}$	\mathbbm{Z}	$\mathbbm{Q}$	\mathbbm{Q}	$\mathbbm{R}$	\mathbbm{R}
$\mathbbm{C}$	\mathbbm{C}	$\mathbbm{F}$	\mathbbm{F}	$\mathbbm{K}$	\mathbbm{K}

The bbm-package has three fonts total:

$\mathbbm{NZQRCFKabc123}$	\mathbbm{NZQRCFKabc123}
$\mathbbmss{NZQRCFKabc123}$	\mathbbmss{NZQRCFKabc123}
$\mathbbmtt{NZQRCFKabc123}$	\mathbbmtt{NZQRCFKabc123}

For more information check http://www.ctan.org/tex-archive/info/symbols/comprehensive/ (in the file of your format check table 135: Math Alphabets).