If you prefer to create a set of bootable floppy disks, you can use the Windows 3.1 Setup Disk:

One autumn evening, as the light angled thinly through garage windows, the community organized a small exhibit. They projected the virtualized desktop onto a wall and played a montage of disk labels and scanned manuals. Stories were read aloud. A teenage volunteer read LASTBOOT.DOC and the room fell quiet. People who had never met his grandfather wept a little—not from sadness exactly, but from the sudden sense of continuity, that the act of making a bootable disk had once been an act of generosity.

Windows 3.1 is abandonware . Microsoft no longer supports it, and you generally won't be sued for downloading a 30-year-old OS. However, copyright technically still holds. The safest legal route? Find an old installation CD on eBay (yes, they exist) or use your original floppy disks.