Visibility: The non-glare surface scatters light, which can cause the contents of the shadow box to appear blurry or less clear. Shadow boxes often contain detailed or three-dimensional items that need to be seen clearly.

Depth Perception: Shadow boxes are designed to create a sense of depth by displaying items in a three-dimensional space. Non-glare Plexiglas can diminish this effect by diffusing light in a way that flattens the visual perception of depth.

Aesthetic Quality: The diffused light can alter the appearance of colors and textures within the shadow box, making them appear duller than they would with clear glazing.

For these reasons, clear acrylic sheets are generally preferred for shadow boxes, as they provide a clear view of the contents and maintain the intended visual depth and detail.