I've viewed the blinds tutorial and made my own version of it. I added a full closed curtain, half open curtain and an option without any window cover. I used a script to randomly assign Mtl IDs to my splines and got a result I'm happy with. (Curtains are very, very simple but it's for an exterior shot so that's okay)
I've made a multi material with a RC color map to add some variation. The problem here is that it views every "part" as a separate item, causing situations where the right side of the curtain is color 1 and the left side is color 2. I can think of multiple tedious workarounds, but since RC is capable of so much more than I can even comprehend I figured there must be a way to properly solve this. Preferably within RC, so without exploding it all and assigning different IDs.
The material I made is included so I've added a We-transfer link for the archive.https://we.tl/t-zv0aCU3oJE