Interesting to guess what it was originally designed for, pretty sure it wasn't original packaging. It would be like an advent calender to open and see what's all in there.
on the OP, what exactly is fake? the dug part? If someone took a Akro sparkler, took the time to melt it down/reshape it, and somehow sell it for a profit? Not sure what you paid but I don't see how anyone would profit from "faking" these examples.
In my collection it would be German Handmade. Orange latticino core with six alternating outer bands in blue and white. Good symmetry. Rough pontils. Probably early 1900's. condition looks good from photos. way less common than white or yellow latticino cores. I wouldn't consider it a $100 marble but I'm thrifty that way.
I keep them somewhat organized and labeled in case I get hit by a bus. I used to be more diligent but when I got to sorting WVS and slags and I wiffle-waffed on so many it just became too time consuming.
I agree slags can be tough especially from pics...but that color...
And pretty sure I'm seeing a huge seam (pic2 and pic 5, along the edge of the white). Nice marble either way
Go for it! Back in the day I wondered about "casing" damaged marbles in a layer of clear glass.
Epoxy would be easier...but not without its challenges if you were going to do a spherical mold there would still be a parting line. And trying to keep the marble centered.
If it were me I'd look at making a domed paperweight or incorporate them in a resin countertop or coaster or something. Post some pics it would be a fun project.