Select a nonslip coating that matches the color of the shower pan.
Use a pumice stone to carefully remove any ingrained water rings or rust marks from the surface. Lightly rub the pumice stone, like an eraser, to wipe away the rings or marks. Be careful not to scrub too hard, as it can scratch some surfaces, including fiberglass.
Rinse the pumice residue, and then clean the shower stall bottom thoroughly with shower cleaner and a scrub brush.
Dry out the inside of the shower stall completely with clean towels.
Open the container of nonslip safety epoxy, and mix it well with a paint stirrer stick.
Apply a single, even coat of the epoxy to the shower stall bottom with the paintbrush.
Allow the epoxy to dry for at least two hours, and then add a second coat. Allow the second coat at least three hours to dry before using the shower.