Can I use square dowels for a Roman Shade?

I'm trying to make a Roman shade for a slider window that is 3 feet high and 6 feet wide. I'm unable to find small diameter wooden dowels 6 feet long. My brother says he can cut some square ones for me and I'm looking for opinions if that will work. Or a way to connect two 3 foot sections. Would duct tape or packing tape hold enough? Or ideas for anything else I can use. I wandered through Home Depot looking for something else. PVC doesn't come small enough, bamboo poles in the garden dept. aren't straight enough. I'm sure one of you creative Hometalkers can solve my dilemma!