This is a rotary knob such as those used for volume controls. The shape of the knob can be adjusted by changing its outer and inner diameters, height and taper towards the top. It is also possible to add an arrow indicator on the top surface, and the shape can be made faceted rather than round. A bevelled edge around the top is also adjustable in the code.
The knob normally uses a set screw from the side. The screw is held by a nut resting on a washer, to ensure strength that allows for tightening. Either a headless setscrew can be used, or an optional recess for a flat head screw can be enabled. It is also possible to disable the screw and nut holes, for press fit on the shaft. The inner structures can be recessed into the knob to enclose the mounting nut of the shaft in the panel.
The knob is designed to be printed upside down, and does not need any support material on printers capable of printing a 45-degree overhang, thanks to teardrop-shaped holes.
To assemble, first insert a washer and a nut in their slots, and then thread the screw in from the side. The washer may need to be pressed in with some force using pliers, depending on the accuracy of the print. If using a headed screw, the knob looks nicest if the screw length is such that the head is approximately flush with the outer surface when tightened.