Leave your wood trim in the room where it will be installed for at least two days. This allows the wood to expand and contract as necessary in the room’s humidity.
Measure the width of the wood trim.
Measure each side of the opening around the edge of the sliding doors and add the width of the trim to each measurement. Take measurements for the top of the opening and the sides.
Cut three pieces of wood trim equal to the measurements you found in step 3 using a handsaw.
Bevel the edges to a 45-degree angle using a miter saw. Bevel one edge of each long piece and both edges of the short piece that fits across the top of the opening. This allows the pieces to fit together like a picture frame.
Apply a thin layer of clear epoxy to the flat back of one of the pieces of wood trim.
Press the wood trim flat to the edge of the sliding door opening and hold it there for several seconds, allowing the epoxy to grip.
Repeat steps 6 and 7 for the other edges, fitting the wood trim to each other at the beveled edges.