Joining surfaces

[FeatherlessChicken]

I have the following test object that I'd like to use "extrude along path" on made of 2 circles I've cut in half, and a polyline. To use the extrude function, I need it as a single surface. How do I combine these into a single surface please?

"Surface->Combine" tells me the surfaces must be part of the same object.
If I use "object -> merge" to combine them then try to combine the surfaces again, it tells me that "all surfaces must be adjacent (with verticies shared between surfaces)."

[Andy]

Combining is for polygons. To make that shape, you'd use the top and bottom semicircles and join them to a rectangle (not lines). It's not the easiest way to make that shape. Before combining, you'd need to put all the surfaces in a single object with Object->Merge. You would also need to make the vertices shared/optimized.


The easiest way to make this shape would be to select what you have made and use Vertex->Create-Convex-surface-object. That will create a single surface in the outline of the shape of the selected vertices, which you can then drag out of the way (and delete the originals?).