You'll need to use a disk image. Try using Disk Utility to make a 1440 KB disk image with no partition map and a FAT filesystem. Mount the disk image and copy your stuff onto it. Then use dd from the ...
You might think that storage is expensive and scarce today, but kids these days have no idea what it is like to scrounge every kilobyte you can. Which is why a floppy disk hack from the early '90s ...