Making Corner Mounts
Phot corners, or corner mounts, are easy to make. Start with a thin, acid-free paper, cut into strips, ½ to ¾ inch wide.
Fold one edge down at a 45° angle.
Fold the other part of the strip down at 45°, meeting the first fold.
Trim the excess. Tabs can be left, or the corner can be trimmed flush..
The corners are attached to the mount board using tape: