The School Bag mystery, solved...

[Hepcat]

Incidentally here are the best pictures I can find of the rare SPP Monster School Bag that's the subject of discussion here:







And here for comparison's sake is the SPP Beatles School Bag:

[Hepcat]

These printer's proof sheets for an SPP sales brochure indicate that SPP also produced Superman and Batman school bags nearly identical to those above:





Plus this Skipper Purse-Pal Doll Case which was available in baby blue or pink is very similar in construction as well:

[RPM]

[Hepcat]

Wow, that's it! The exact same bag as the Universal Monsters, Beatles, Superman and Batman ones! So SPP made at least five anyway in the exact same style.