From BlenderWiki

Skinning

Skinning is the fine art of defining a surface using two or more profiles. You can use skinning to create a shell to represent an object, like a sailboat hull. You also can use skinning to clothe a character, for example to model a jacket for a character.

Notes on Clothe a Character

To clothe a character, you can use the technique described in here to skin the base character mesh, or use the base mesh itself as a starting point to define other related items. There are at least three ways to model clothing. First, you can just paint the base mesh of the character, like the naked tatooed lady that lurks in Germany. This is good for swimsuits and lycra/latex that is very close-fitting.

Second, you can copy the base mesh of the character, scale it outward a bit, and add details like belts and such. In these first two approaches, you let the armature deform the mesh as the character moves. These are good for game characters and most applications. It provides a very close fit to the model as well.

Third, with 2.46, you can drape cloth over your model, and stitch and sew it. For this third option, you do not use the armature to deform the clothing, but instead let the simulation deform the cloth based on the body mesh that is moving. This should be good for long dresses and capes, as it evolves. Presently, there is quite a gap between the mesh and the cloth which can be visible and is not realistic, it is very compute-intensive, and the body mesh tears through frequently. However, it is stable enough to be used and improved upon.

Skinning to define an Object

In Blender you do so by preparing as many curves of the the desired shape and then converting them to a single NURBS surface. Once you have the skin defined as a NURBS surface, you can convert that to a mesh for more detailed modeling and/or texturing.

As an example we will create a sailboat. The first thing to do, in side view NUM3), is to add a Surface NURBS Curve (Add>>Surface>>NURBS Curve).

Be sure to add a Surface curve and not a curve of Bézier or NURBS flavour, or the trick won't work (A Surface curve for skinning.).

If you are using Blender v2.42a, click "Endpoint U" in the "Curve Tools" window to make the curve stretch between the endpoints.

A Surface curve for skinning.

Give the curve the shape of the middle cross section of the boat, by adding vertices as needed with the Split button and, possibly, by setting the NURBS to Endpoint both on 'U' and 'V' as needed. You do this by clicking the Endpoint U or Endpoint V buttons in the Curve Tools panel under the Edit buttons (Profile of the ship.)

Profile of the ship.

Now duplicate (SHIFT-D) the curve as many times as necessary, to the left and to the right (Multiple profiles along ship's axis.). Adjust the curves to match the various sections of the ship at different points along its length. To this end, blueprints help a lot. You can load a blueprint on the background (as we did for the logo design in this chapter) to prepare all the cross section profiles (Multiple profiles of the correct shapes.).

Note that the surface we'll produce will transition smoothly from one profile to the next. To create abrupt changes you would need to place profiles quite close to each other, as is the case for the profile selected in Multiple profiles of the correct shapes..

Multiple profiles along ship's axis.

Multiple profiles of the correct shapes.

Now select all curves (with A or B), and join them by pressing CTRL-J and by answering Yes to the question 'Join selected NURBS?'. The profiles are all highlighted in Joined profiles..

Joined profiles.

Now switch to EditMode (TAB) and select all control points with A; then press F. The profiles should be 'skinned' and converted to a surface (Skinned surface in edit mode.).

Skinned surface in edit mode.

Tweak the surface, if necessary, by moving the control points. Final hull. shows a shaded view. You will very probably need to increase ResolU and RelolV to obtain a better shape.

Final hull.