@RonGilbert I am very happy with the 3,5″ floppy disk and the game box and I think it creates a good retro feeling especially for an adventure game fan from the late 80s and early 90s. 
In Sep. 2014 I bought the “Humble Indie Bundle 12” package which contains a physical game box (designed by fangamer), a floppy disk (with very simple web game, some old school designed websites), the soundtrack on vinyl record, and other items.
In general it was really great but the floppy disk was not 100% correct recorded, creating an readable disk image with KryoFlux does not work without some adjustments. Nowadays it is hard to find some one to record (and also correctly record and copy) floppy disks.
The other thing was the carton, of which the “Humble Indie Bundle 12” game box was made, it was too thin and too small, so for me no real retro feeling come up. In contrast to that the Thimbleweed park box is really retro, it seems to be much more robust, have the proper dimensions and is very good designed. I think it was a good idea to spend more time and money on a good box instead of creating only some kind of unstable ‘box’. 
The idea to ship the soundtrack on a vinyl record was great. Is there a chance for an “Thimbleweed park Soundtrack” vinyl record or an analog audio cassette? I would buy both
Also see Custom cassettes.
Do you mean 5,25″ or 3,5″ floppy disks?