Which way around, for cutting the eggshell in half? A Raw egg?!
The thin, small diameter disks aren't intended to be panel cutting discs.. the disk doesn't approach a large surface squarely, like a circular saw blade generally does, for example. Still, with a steady grip, one can make cuts in wide areas while maintaining the pitch required. The small disks, even when used with the Dremel 90 degree adapter still don't have large enough diameter to cut perpendicularly in a large/wide surface.
One fairly useful purpose I've found for the thin abrasive disks, is to cut a clean slot in a stripped/deformed screw head to make removal possible with a flat blade screwdriver, and if the screw head is recessed, the small disks only cause minimal damage to the surrounding material. When I've worn the small disks down to a smaller size, I leave them mounted for uses where a fresh full sized disk wouldn't fit the application.
The dirt cheap diamond grit metal disks are great for a lot of cutting uses too, and almost unbreakable (can't imagine how one would break them, but I suppose it's possible).
A 1/16" or smaller veining cutter (ground cutting teeth not abrasive) works very well in a Dremel with the router base accessory, for cutting out curvy lines in acrylic sheet or other suitable materials.
The old Handee accessories included some unique drills, in that the cutting section was ground as a very short "head" with 2 flutes like a regular drill point end, with a thinner shank section behind it.. very well suited for using with a small motor, low-powered tool.. less rubbing on the sides of a hole.
I suppose the machines that grind the various types of miniature cutters must be fascinating to see or watch in operation.