Water can be simulated in dioramas and model landscapes using epoxy resin. If epoxy is left alone, it dries to a flat surface, giving you a lake on a windless day. However, a calm scene may not be what you are looking for in your landscape. You can use epoxy to create an impression of moving water by agitating the surface while the resin is curing. This will give an illusion of motion to your landscapes and create drama in the scene it represents.
Prepare the base of the diorama. The area where the water will be must be finished before pouring any resin. Paint the bottom and glue down any effects like sand, rocks, or water plants. The glue is important to prevent any items from rising into the resin and making it cloudy or full of debris.
Put on protective gloves and a respirator mask. Epoxy resin has less fumes than other types of resins, but you should still work in a well-ventilated area and protect your lungs from fumes with the mask. The gloves will protect your hands in case of spills or enthusiastic splash-making.
Mix a small amount of the epoxy resin and hardener according to the manufacturer's instructions in a disposable bowl or cup. Add a drop of paint to colour the water, to match your scene better. Add more paint for deep or murky water and less for a clear, lightly tinted effect. Stir the mixture with a disposable stick. The epoxy will ruin the stirrer so don't use anything you want to keep.
Pour the epoxy into the deepest part of your water area in your base. This first batch of epoxy is the very bottom of your water and will be poured flat. Epoxy should only be poured to heights of roughly 1/8 to 1/4 of an inch, or the drying process will create too much heat and the resin will become cloudy. You may need more than one layer to fill your base. Allow the bottom layer to dry completely.
Mix another small batch of resin and hardener. If the second layer is not the top of your water, add a small amount of paint. Use less than in the bottom layer to create a graduated, clearing effect as you work up to the top of the water. Repeat until you are close to the top.
Mix a clear or nearly clear batch of resin and hardener for your top layer. Add any prop items that will be sticking out of the water; this layer of epoxy will glue them into place, and form the illusion of being slightly submerged. Pour the layer of epoxy and let it start drying.
Use a stirring stick to create waves and bumps in the epoxy while it is still syrupy. Move the stick consistently but not fast enough to cause air bubbles. Pull it up out of the epoxy to make small, rising splashes. Splashes and whitewater should be rough and more spiky, so keep going until the epoxy is gelled enough to hold the shape. If you stop too soon, your splashes will settle into gentle waves.
Paint the tips of any splashes with a white paint. Use the paint sparingly or you will cover your clear water. Once you are satisfied with the splashes' paintjob, paint a thin layer of clear epoxy or lacquer over it to protect your epoxy waves.
Epoxy can be layered on top of itself, so if your waves or splashes aren't big enough, build them up. Use a brush to daub resin on existing waves to make them taller. Thicker resin that is farther into the drying process will hold points for violent splashes better than syrupy resin.