I broke these old parts after draping a rope light across the top of my blinds, so I traced their design and printed some replacements.

Prints fine without support, though the “webbing” will be a little rough on one side; since this part is just support for a covering strip in the first place, this isn't really a big deal.

Source

This model is composed from two SVG outlines and one OpenSCAD file, available on GitHub.