Pleated shade holders, with and without fixing screw, for shades using a square mount system small lug, like those from https://www.schattenfreu.de/ for .e.g. Can be installed with suitable strong tape (VHB for e.g.), optionally with or without a screw. To install you need to print 4 of these, 2 of each pair, or combine with the provided mounts from the manufacturer. Suggest printing like in the image attached using your preferred filament and settings (should be strong enough to carry the weight of the shade though), no need for supports.
The author marked this model as their own original creation.