I have been searching for this for a while, I have a Chendrone Squirt V2. I have broken an arm on it and wanted to have something without ducts. So I have been using my google fu a lot, and haven’t really come up with anything. Most frames for 3 inch props have mounting holes for 20×20 or maybe slightly bigger, but very few had 30.5×30.5.
You can find it here:
https://www.amazon.com/Hobbies-Realacc-Martian-Wheelbase-Carbon/dp/B08P5CBY92