This is very important. Nothing more infuriating than getting a .sit over to a System 6 Mac, and then not being able to open it because it was made under OS X and you didn't know it. I use either one of two formats: Disk Copy 4.2, or if an archive Stuffit 1.5. Anything can open Stuffit 1.5 archives, and even System 6 Macs can straight mount DC42 images with the appropriate software. Compressing things into ZIPs or later Stuffit just stinks and makes it hard on people.Please try to do it on period hardware, because you should be testing it on old hardware anyway if possible.
Macintosh Garden is full of System 6 and 7 software that people have wrapped up in archives that won't uncompress on computers that run those system versions. Its a pain, I have to keep a Pismo to hand to recompress files stuffed with more recent OSX versions of Stuffit, or the Archive Zip option in MacOS X. I used to /only/ have an SE in the house retro mac wise so it was even more of a pain.
As for the initial question, I have just started using my AppleSauce to make archive copies of things. For garden variety stuff, it is a very easy way to make Disk Copy images on your current Mac. That is very easy: attach your external SuperDrive (or 800k drive), use the modern AppleSauce software, and it will spit out a DC42 image. No intermediate machine necessary. You can also make Flux-based .A2R images. It is very difficult for the casual user to just write these back to a new floppy, however (Shadowgate, for example, has thrown the cadre of disk-crackers into a search for how to crack it and duplicate it, requiring different reads. They are still stumped as of this writing, and I am awaiting them to have free time to get it right!). Once they figure it out, they actually have to tell you how to set the start sectors of the disk before it is written back: far more low-level stuff than I will ever understand, so I am totally dependent on them.
The only stumbling block is the price: be willing to shell out almost $300 for the AppleSauce. I didn;t buy one till I sold a bunch of my stuff for that reason.