
I started with gluing layers of
styrofoam together in the basic shape I wanted. Then I used a hobby knife to cut out the
river bedding. It should not be a smooth surface, that will only make the next step more difficult. Do not cut deep unless that is the effect you want, I will fill it up. I left an empty space for electricity equipment under the base in the back in case I want to use lights together with it. A bend at the top of the riverbed makes the base easier to integrate in a landscape - the river can appear from behind rocks or trees.

I added a thin layer of air dry clay in the
riverbed and made it smoother with a tool (a butter knife will work if you don't have a tool). Then I started to add the shape of the flowing water. It does not have to be very detailed or perfectly done - this is just the base for the water. Make sure the
river bedding is filled at the edges. If the clay doesn't want to stick dampen the
styro slightly or you may need to make the
styro surface more rough.

Continue with the whole waterfall in the same way. If it is a large area you have to do the next step before the clay has dried too much.

The whole
river bedding is filled and I started to add the currents in the water and the whirls- under the waterfalls and where the water is forced to change direction by rocks etc.

I painted the base around the waterfall in a basic landscape color, brown in this case. Make sure the paint is
waterbased or it will melt the
styrofoam. (I am using my kids poster paint from the toy shop...!) The paint will mostly be covered later but I don't want the white
styro base to show.
I shaped loose rocks from the clay and added them into and around the river bedding. I didn't make them very smooth, they should be irregular and have some cracks.

When everything was dry I glued the loose rocks into place and painted them very dark (black) and the water was painted blue. Do not worry about the colors, the idea is to cover the
styro and clay at this stage. After a while I checked it and added more paint (made thinner with water)where the
styro or clay wasn't completely covered.

The rocks were brushed with medium grey, without covering the deeper parts and then I dry brushed the areas sticking out with very light grey to highlight them.
I did this to all the rocks and also made the blue water a bit darker with grey paint. It should be darker now than the final result.

My rocks have moss so I brushed the areas I wanted mossy with dark green, avoiding to add paint in the deeper areas. I also painted some darker areas in the water- those will be in the shadow of plants later.
A glossy transparent paint thickener paste was added into the river bedding to create the effect of water. Be very careful with how this is done as this pattern of flowing water will be showing when it is finished.
When the paste was completely dry the final step: Dry brushing the paste very lightly with white or very light grey paint.
I attached this base to the rest of my landscape using wooden sticks or tooth picks instead of gluing it - I want to be able to use it again in several displays.
Plants and scatter material was added for the finishing touch.