An empty holster still has to look like it fits something
Leaving the firearm out is the right call for this category, and it creates a small photography problem. An empty holster can look like a shapeless piece of plastic. The image has to show the retention, the mouth of the holster, the clip and the cant without the thing it holds.
Angle does most of that. Shoot the holster at three-quarters with the mouth tilted slightly toward the camera, so the opening and the trigger-guard moulding read as shapes. A second shot from behind shows the belt clip or paddle, which is half of what a buyer is choosing. On the white-background image, turn the holster just enough that the clip shows in the same frame, so the main image answers both questions. The examples on this page start with an empty kydex holster on slate, and the short clip was made from that still.