Room Treatment for Corners - Recommendations?

Do folks have any recommendations for ceiling corner room treatments? I had read some good reviews of such triangle-like treatments from Eight Nerve, but the company appears to be out of business now.

I may also want to try some other treatmetns too, but corners are my priority just now. I'm improvising some pilates tubular exercise type thingies in on the floor in the corners behind the speakers currently, but am guessing I may get better results from proper tube traps, although they can get pricey and I'd prefer to focus on more cost effective solutions.

Any ceiling-corner solutions out there?