These fancy 8-faced spheres come in two sizes and can be used for precise scanning using 3D scanners, 6mm cylindrical magnet can hold the marker ball firmly attached to any ferromagnetic surface for quick and easy scanning without the need for sticking markers to the surface.

There are two sizes and two variants to each marker ball, the small ball for 3mm marker with or without a hole for magnet, and the same for the big ball for 6mm markers
The design caters for 6x30mm neodymium cylindrical magnets that need to be press fit into their respective holes, i highly reccomend a vise for this purpose as neodymium magnets are quite brittle so they cant be reliably hammered into place, the tight fit is meant to avoid the need for glue. the odd shape of the top of the ball makes it tricky to hold againt the jaws of the vise so i added little flat-top adapters to first place the balls into then place against the vise, insert the magnet and squeeze until the magnet wont go any deeper. You can use shorter magnets but these may not hold the balls firmly in place during scanning. You can also use 5mm magnets instead and just slide them in and glue them in place using CA glue without the need for vise

Each ball (small and big) has 8 indented spots for sticking on standard markers (creality branded markes in my case) If they dont stick very well for you then you can help them out with a tiny dab of CA or maybe hot glue (didn't test that one) The geometry of these balls makes it so that scanner sees at least 2 markers at any time even when viewing the subject from odd angles which makes it very easy and quick to scan complex objects.

If the object isn't ferromagnetic, you can still stick the balls on subjects temporarily using sticky putty

If you dont want the magnetic feature, there is also the non magnetic version with flat bottom for placing the marker balls flat on the subject or around it

For storing the marker balls when not in use, i designed a neat print-in-place pelican case. The case fits 10 big marker balls and 10 small ones. It just about fits on a 256x256mm bambulab buildplate. It uses a living hinge for both the case hinge and two latches, you print it laying down flat then carefully pop it of the build plate without tearing the hinge and carefully blast the hinge and latch with a heat gun to briefly soften the plastic enough to rotate the two halves of the case into closed position, then let it cool and and the case with hopefully remain closed when latched closed and open without snapping the hinge. treat this like a work in progress bonus as i cant guarantee any longevity or consistency with this design.

Marker balls can be printed with no supports with any standard filament, the layer height doesnt really matter, so does the color and finish, the wall count/infill is up to you as it's a game of balance between high weight = stable marker, immune to vibrations and low weight = strong magnet attraction, less prone to knocking down mid-scan

One additional tip: i reccomend sourcing the magnets locally for wherever you are, as ordering neodymium magnets from places like aliexpress tends to be a massive pain, they are pretty expensive and take forever to arrive due to customs shenanigans, at least in my experience.