Curtain rails as cable/wire ducts

Here are some holders so that you can use curtain rails as cable/wire ducts. The curtain rails are made of aluminum and are common in Denmark, and probably also in many of the neighboring countries. So they are readily available and cheap here.

We have used the end stops from these drawings for a simple cable duct for a laser cutter we are building. We wanted most of the material used to be aluminum or similar in color. I've attached two photos from that build.