Making small accurate cuts on a miter saw is safer when using a zero clearance fence.
Diy miter saw zero clearance fence.
Cut two pieces of stock about the same length as the base or even longer if you want additional support for long pieces of molding.
The insert is a so called zero clearance but that s not really effective on a miter saw like this other than to limit the amount of sawdust that collects in that slot.
That s especially good for smaller or thin pieces.
The major benefit is the support it gives to the stock right where the blade is cutting.
Join the strips of wood together using some glue and 2 inch brad nails.
Cut another piece 4 inches wide for the fence itself.
Cut a piece of plywood or mdf 7 inches wide to use as the base for your fence.