Some retro archivists create hybrid CDs that boot to DOS, then automatically launch the Windows 3.1 setup. (an abandonware museum) hosts "Bootable DOS CDs with Win3.1." These are technically two operating systems on one disc.
Driver hunting is still required for high-res graphics and sound. windows 3.1 bootable iso download
Softonic, CNET Download, and any "Windows 3.1 ISO Downloader" EXE files. These are guaranteed malware. Some retro archivists create hybrid CDs that boot