Abstract: A method of manufacturing a drainage base tray for a shower, the method including the steps of: a) providing a foldable sheet of metallic material; b) cutting a one-piece blank from the foldable sheet of metallic material; c) folding the blank along at least one folding line in order to define at least one corresponding slope within the blank, the slope having an upper portion and a bottom portion defining a sloping gradient; and d) providing the blank with a draining hole adjacent to the at least one folding line and in proximity of the bottom portion of the slope, for allowing waste liquid to drain via the draining hole of the drainage base tray. Also described is a resulting shower drainage base tray, and a one-piece blank made of metallic foldable material and having portions for manufacturing the shower drainage base tray. The present system also concerns a shower drainage kit including a grill component positioned, shaped and sized for placement over the shower drainage tray.