A 3D Marker pyramid to be used with a 3D Scanner. Easy mounting on magnetic surfaces/flat surfaces. Reduces waste/cost of always disposing of markers after a single use. For permanent use with a magnet, you may want to glue in the magnet.

I also have other shapes on my page.

What you need besides the print (per sphere):

3x 10x6mm Reflective Markers (example 1000pcs from Aliexpress)
1x 6mm Dia Spherical Magnet (I use 20mm length)