Steps
Measure the mirror so that you know how much material you will need.
Select the type of molding. It’s best to select one that will math the rest of the molding throughout the home.
Paint all of the trim the desired color and allow to dry completely.
Glue pieces of the MDF together, pressing firmly and allow to them to dry completely (at least two hours).
Run a bead of caulk along seam joints. Smooth caulk line and wipe away any excess. Let dry one hour.
Apply touch-up paint to the frame as needed.
Apply another layer of paint to the entire frame and allow it to dry completely over night.
Apply paneling adhesive along the places of the wall where the frame will be attached.
Carefully press the frame into place ensuring that it is even and level. Secure it further with the clean release tape.
Run a bead of caulk along any gaps at joints. Smooth caulk line and remove any excess. Let dry one hour.
Apply touch up paint as needed to the frame and walls.