+1 on the suggestions so far. I would go for a clear acrylic or polycarbonate front so that you can see blinky lights and things inside. A bit of silicone sealant around the edges of components that stick through.
My personal take is that waterproofing is a good idea provided that you can vent heat from SSRs effectively. It does depend where your controller is mounted. If the controller is mounted on a brewing cart, waterproofing is more of a priority than if it is wall mounted 6 feet away.
I have certainly used tupperware for enclosures but only low voltage.