John, I tried doing the same exercise a little while ago and failed miserably.? Free version of Fusion restricts one operation in the process which has to be done manually triangle by triangle.? My file had many facets, but that vase has a crazy number, so that route is a non starter.
Don't bother with any of the on line converters, they are a waste of time.? I eventually found a SolidWorks version which I managed to get converted on the system at work.? As many modern slicers and printers can use step files directly (claiming better results), perhaps try to find the same or similar vase in the required step format.
Also I think Fusion free version can import 3mf files and just ignores print side of the file.? If you can find one of those I'd be happy to try and convert/alter it for you.
