Hi naoky, thanks for reporting this bug!

It seems to be caused by some specific shape in those particular fonts. I tried with about 20 different fonts over here and I could not seem to repeat the problem.

If I can repeat the problem while running over here, it makes it a lot easier to try and debug it.

Could you please let me know the name of the font that you are using there, and also please attach (or e-mail to me at moi@moi3d.com) a 3DM file with the curves in it so I can try to repeat the extrusion problem over here?

Occasionally some fonts have things in them like self-intersections which don't really affect the regular 2D text display (which they were originally designed for) but can mess things up when trying to make them 3D. This could possibly be something related to that, but there is supposed to be a mechanism in the Extrude command that tries to use a consistent direction when extruding a bunch of things all in the same plane. That does not appear to be working in this case, and if I can repeat the problem over here I'll see if I can get it fixed up.

- Michael