You need a 3d modeling program to make your own clothes. There are a wide variety of modeling programs out there that span the feature and price range, from high-end to freeware.

I'd suggest you try some of the freeware or lower priced modeling applications to see if this sort of thing is up your alley. Check out Wings3D or 3DCanvas. Wings3D is freeware and 3DCanvas from Amabilis has a free version of its modeling application. The pro version of 3dCanvas is only $69.

Nuke