Depends upon which language you would like to use. For creating dlls with C++ you can get Dev C++ for free at http://www.bloodshed.net/devcpp.html . Obviously it is not a tool, it's a full featured compiler and ide for C/C++. For this compiler have a look here:
http://blitzbasic.com/Community/posts.php?topic=51944#579729
Good luck !
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www.moonworx.de
http://blitzbasic.com/Community/posts.php?topic=51944#579729
Good luck !
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www.moonworx.de