Wipe down the open space where the soap tray was originally installed with a dry cloth. Glue sticks best to dry surfaces.
Sand the back of the detached soap dish with coarse sandpaper. Sanding removes old, dried glue from the soap tray while also roughing up the surface for better adhesion.
Spread waterproof super glue generously over the back of the soap tray.
Press the soap tray back into place on the shower wall. Hold the soapy tray in place for 30 seconds to one minute.
Wipe away any glue that seeps out from behind the freshly glued soap tray with a damp sponge. Wait 24 hours before taking a shower to give the glue time to set before being exposed to moisture.
Wipe down the broken tray with a dry paper towel to remove all moisture.
Spread a line of contact cement on the tray's broken edge.
Press the missing piece firmly into place over the contact cement. Hold the broken piece in place for 30 seconds to one minute.
Wipe away any excess contact cement with a damp sponge.