The bevel will enhance your work by adding depth. The English bevel and the French bevel differ in the angle of the cut in the chosen card stock: oblique, at 45°, or straight, at 90°.
What you need to know
The 45° bevel (English), suits most documents. You may make it separately, then decorate it with various materials (colored paper, golden Kraft paper...), or make it directly on the edge of the mat.
The straight bevel, at 90°, adds a contemporary note. You can stack several, with smaller or larger setbacks, like stair steps.
Make the bevel in the mat edge
Cut a sheet of heavy card stock, 3 mm thick, the size of the framing package.
Put the mat on top and mark the contours of the mat opening.
Cut straight bevels with a utility knife, as with any other cardboard, against the length of a heavy straight edge placed against the reference marks.
Cutting an English bevel free hand is somewhat tricky. Preferably use a sliding straight edge, equipped with a rail allowing the insertion of a utility knife with an adjustable-angle blade. Take into account the bulk of the system when making your reference marks.
Cover a bevel made separately
Prepare 4 covering strips.
Width = 3 cm
Length = that of the bevel side + 3 cm.
Cut one end of each strip at 45°. Fold the latter in half lengthwise.
Place the first strip on the back of the bevel, cut the second end at 45°
Glue the inside of the strip, place the fold against the bevel. Smooth with a bone folder, on and under the bevel.