Hi Woodsy,
here are some of my Giant robot/Anime pencil cases, mostly bought in the late 70's, to mid 80's. I have a few more, but this will give you the idea...
The ones on the left are very cheap construction, being made from vacuum formed styrene trays with a cardboard cover, heat sealed inside vinyl sheeting. They are almost all held shut with magnetic latches.
The more luxurious double layer versions boast two opening covers. These feature cover art with Bootleg Gundam, Southern Cross aka Robotech Masters and Arrivederci Space Cruiser Yamato.
The two edge on examples aren't Sci Fi, but both have much more complex locking systems. The lower has a toggle clasp and the upper a weird radio tuner style that requires the user to twiddle the knobs until the needles in the dial match up!
The Crown jewel of this small collection is this transforming Daitarn 3 robot which features a number of easily lost components!
See what you think.
Looey
Oz Base