How to create a rounded cap?

I want to cap the ends of the surface created with sweep command.

Normal “cap” command creates a flat cap. I would like the cap to be rounded.

What is the easiest and idiomatic way of doing this in Rhino?

It really depends on the shape that needs to be rounded. There are a few possibilities that come to mind:

  • Create a Sphere of approximate size, cut it in half and create a BlendSrf between the sphere edge and the surface edge. Added bonus: continuity control.

  • Draw a rounded curve from surface edge to surface edge and use Sweep1 to “rotate” it.

  • Create a Sphere of approximate size, cut it in half and use Sweep2 on the edge of the surface and the edge of the sphere with an appropriate sweeping curve.

Well, this will depend on the shape of the opening to be capped. If the surface edge to be capped is composed of one smooth curve (no sharp corners) - or a series of curves that are at least tangent - then you might try Patch with the Tangent option (using the surface edges themselves, not duplicated curves)… Otherwise, the best way to do this is more or less on a case-by case basis. Different geometries will require different approaches.