Sketches are 2D. The binder twists around the planar spine and is 3D. What did you plan to do with the sketch - you may be able to use the Binder in its place.

Use a PartDesign SubShapeBinder - the green one. Select the edges, then click the SSB.

Here's a cut at it - add some fillets to your taste to make it more organic.

If I open the enclosed file (created with 0.22.36904) in 0.21.2, the sketch is correctly located on Edge6, but is unsupported. Change the cube dimensions and the sketch will not move. When created the sketch was supported. This I understand came from a naming conflict, so that Support was renamed At...

In the longer run it would be nice to see documents, all in one PDF, better describing the definitions of: Support, Map Mode, Map Reverse and of course the various methods of attaching these to points, edges, faces etc. Basic Attachment Tutorial Part EditAttachment O-X-Y Type Attachment Modes https...

@Roy_043 's process of creating a curve from its projections on two orthogonal planes is automated in the Curves WB - the Mixed Curve tool.

wmayer Fixed in OS: macOS 14.4.1 Word size of FreeCAD: 64-bit Version: 0.22.0dev.36904 (Git) Build type: Release Branch: main Hash: 0622cb784e199053656b50854e92eff806130408 Python 3.11.8, Qt 5.15.13, Coin 4.0.2, Vtk 9.2.6, OCC 7.7.2 Locale: C/Default (C) Installed mods: * MeshRemodel 1.9.22 * Dynam...

You should be able to use PartDesign LinearPattern

Mesh WB|Flatten Face should handle it - but it doesn't like a periodic surface, so I sliced it in half and flattened that. Curves WB requires the face to be flattenable without distortion.

How do you get a blank support system here? I don't recommend to use unattached sketches in PartDesign. You can achieve via RMB menu->"Attachment Editor" and there you clean all input fields They aren't unattached - but apparently on opening an 0.22 generated file in 0.21 the Support prop...