>>Do I need to close off one end somehow?

Use the cover surface to close off both ends. Then use the stitch into solid tool.

Tim

Hi Paul


See attached cover both sides with the cover tool seems ok but , I get the error you posted by using the cover with guide tool.

Regards

Jason

Generally, to make a solid out of surfaces, the surfaces must create an enclosed volume, no gaps or holes.

Join all surfaces together.

Stitch into solid.

Going from facets (polygon mesh) is a slightly different route. Potentially a lot more work, but not necessarily. Try to avoid facets in most cases. Polygon meshes are great for most animation and rendering Apps (DWG,DXF,OBJ,3DS, etc.) but not for mechanical design or surfacing (i.e. NURBS, T-Splines technologies) Apps. A faceted mesh is a collection of many 3 and 4 sided faces (all edges are linear) that are filled between edges to form what looks like a surface (at least it is usually defined as one), but if the spaces are not filled then you would have a wireframe only. NURBS are also 4 sided but the edges can be curves, creating complex surfaces between the 4 edges and mathematically interpolated between the edges, resulting in a clean surface (usually). Its the difference between a sheet of flexible rubber (NURBS) and toothpicks glued at their tips with stiff paper board filling the voids. I've dealt with this issue for the past 12 years, it takes a while to get your head around the concepts.

I know there are different ways to describe forms mathematically, but I don't have the time and education to get into the numbers that describe solids.