Showers and bathtubs usually contain strips that clip onto the shower glass to prevent water leakage. These strips are typically made from a heavy plastic such as PVC and are available in many different colors and styles. Mounting them to the glass is easy; all you have to do is push the strip firmly onto the edge of the glass to create a seal. Before you can mount these strips, you must trim them to the appropriate length.
Hold a length of the plastic strip against the shower door to which it will adhere. Ensure the end of the strip is flush with the end of the shower door.
Mark the size of the shower door on the strip with a marker.
Place the strip on a flat surface and position it so the end you need to cut hangs slightly off the surface.
Cut through the mark you made, using a hacksaw. Use long, steady strokes to create a straight, even cut.
Use 150-grit sandpaper to smooth the cut end of the strip if it's rough.