This is a very simple handle for a 1/4-inch screwdriver bit, intentionally designed with a special shape that serves the dual purpose of being used for new Scarf Joint Seam testing models.
Bambu Studio or Bambu Handy does not support this new seams yet. For this time, to testing Scarf Joint Seams, you must use OrcaSlicer 2.0, download Hex_Bit_Scarf_Seams_Test_OrcaSlicer.3mf file and import it to OcraSlicer 2.0 manually (see third picture).
PS: Holes for Magnets Ø6x2mm are integrated, nice handy little tool after testing :)