I've got a hardware TX-16W and want to try out the contents of my own sample-disks with Cyclone and wonder how I can create a suitable disk image on my Mac?

I'm assuming Disk utility will do it, but how? I've done it years ago and tried it again, but couldn't find any presets for 720 KB floppy disks (or I didn't do it correctly, havinglikely forgotten the procedure after all these years) or... in true Apple fashion I wouldn't be surprised if they've removed whatever they found obsolete. I'm using OSX 10.11 (El Capitan).
I don't mind doing it in the OSX Terminal if necessary either.

I did read the Cyclone FAQ and also a posting entitled
"TIP: Loading AIFF files into Cyclone using a floppy image" which refers to the FAQ page with a blank disk image download available, but unfortunately those links no longer work.

Try our online image creator if you have not done so.

https://soniccharge.com/floppybaker

If your sample-disks are in the original Yamaha format you will need to use the import function. For more information see "The Import Routine" section in the Typhoon 2000 addendum