Lately I've been building MS-DOS and remember a self extracting Windows 3.1 for workgroups file that gives me all of the files not in a floppy but in a self extracting executable to just record onto CD-R or CD-RW and move into my MS-DOS installation. The file is 'en_wfw311.exe' and is subscription only. You also need the Microsoft MS-DOS CD-ROM Extensions 1.25. Theoretically you can find all of the 3.1 source from old samples and NT4/2000/2003 source. All of this old software I visualize in virtual machines.
"Source code for Windows 286/386/3.1 can be found with the leaked NT 4.0 source in ~\private\mvdm\wow16\kernel31