A good display mount is first functional, and then as unobtrusive as possible. The observer's eye acknowledges the mount but does not concentrate on it. There is nothing quite so distracting to a small mounted artifact than a crudely finished Plexiglas base. This is because the nature of Plexiglas calls for crisp lines and defined and transparent edges. Choose mount materials for their inertness, appropriateness to the job and their unobtrusive appearance.
Light is reflected and refracted differently through clear plastic than other materials.
Wood, for example, is different than plastic and should be treated in such a way that it harmonizes. Imagine a fine print framed with a mat that has crookedly cut edges. Or the fabric-covered base of a display case covered in creases. Work neatly and carefully, even if it takes a considerable amount of extra time. Often the display mounts in a museum will be made with the material which is most familiar to the staff member responsible for them.