Found Mark_of_the_Inquisition.stl somewhere on the webs ... not sure where.

Created Mark_of_the_Inquisition - Double sided.blend to create a double sided (and slightly thicker) version, which was then exported to "Mark_of_the_Inquisition - Double sided-Mark_of_the_Inquisition.stl".

"Mark_of_the_Inquisition - Double sided-Mark_of_the_Inquisition.stl" was then renamed to Mark_of_the_Inquisition - Double sided.stl because JLC's 3D print service doesn't like long names.

Created Mark_of_the_Inquisition - No frame.blend by importing Mark_of_the_Inquisition.stl into Blender, deleting all the vertexes related to the frame, moving the rest down by 2.996 mm in the Z directory and then applying a mirror modified (mirroring on the Z axis). This was then exported to Mark_of_the_Inquisition - No frame.stl.