A friend and I wanted to make a gaming table to play Warhammer on. We decided on a modular design because 6 2'X2' sections are easier to store and carry than a full 6X4 table. The modular design also gives us a lot of options when setting up the table. The board consists of four sections with hills and two flat sections, comparable to the GW gaming board. Each of the hill sections has a hill on one corner with a hill edge and a cliff edge. The project cost around $80 including paint.

Step 1: Tools/Materials

Tools

Skill Saw
Band saw
Straight edge clamp
Paint brushes of all sizes
Rock mold (you could use carved styrofoam or rough tree bark instead)
Hobby knife
Serrated knife
Drop cloth
Sand paper

Materials

6'X4' ½ inch MDF (I used 3 2'X4' panels)
4'X4' 1 inch Polystyrene (extruded Styrofoam)
Fine grit sand (about 2 gallons)
Wood Glue (about 40 fl Oz)
Paint
small pebbles (sifted out of sand)
Lightweight Hydrocal (1/2 gallon)

Step 2: The Board

First you need to cut the board sections. You want six 2'X2' sections of medium density fiberboard.
I bought 3 2'X4' panels of MDF. I used a skill saw and a straight edge clamp to make sure the cuts were straight.
I trimmed the long edge down to exactly two feet, then cut the boards in half, measuring 2 feet from one side, and finally trimmed the three panels that were about an inch longer than 2 feet.
Draw out the basic shape of the hills on the board sections, mark where you want hills and cliffs.

Step 3: Hill Edges

To make sure that all of the hill and cliff edges lined up, I cut out profiles of the hills I wanted to build. I first cut 2'' wide strips of particle board. Any thin board would work. Next I drew out profiles of the hill and cliff edges and cut them out with a band saw. I sanded down the cut edges to make them look nice. The third picture shows the basic frame of the hill. Finally glue down the edge pieces with wood glue and clamps. Make sure that you are consistent with which piece (hill or cliff) goes to the edge of the board (see picture 4) .

Step 4: Hills

For the basic structure of the hill cut out sections of extruded polystyrene. Make sure the hill edge side covers the profile piece. The cliff side edge should come within an inch of the profile piece. I saved some polystyrene by cutting out the inside corner. If you do this leave a small piece of polystyrene in the corner to support the next layer. Glue the polystyrene to the base and the profile pieces with wood glue or hot glue. Wood glue works better in my experience. Cut out and glue another layer for the top. The hill side should be a little shorter, but the cliff side should line up with the piece below it (see picture 2).

Step 5: Cliffs

Start by making a 3 or 4 full rock molds. Glue the big sections to the ground along the polystyrene. To get the rock chunks to fit together better, use a band saw or a file to cut them. Next use smaller rock chunks and rough pieces of polystyrene to fill the rest of the cliff in. On the hill edge cut the edges of the polystyrene boards to start smoothing the hill.

Step 6: Rounding Hills

First cut off the edges of the Styrofoam with a serrated knife (1st picture). Next use a file/rasp and then sand paper to further round the hill (2nd picture).

Step 7: Filling Cracks

To fill in small and hard to reach areas we used a mixture of shredded tissue and pva glue. soak the tissue and push it into cracks between the cliffs and the hills.
Next we used more lightweight hydrocal. we poured it over cracks and other areas we wanted to fill and then used pieces of cardboard and our hands to smooth it out.
After the filler is done we wet sanded it until it was smooth.

Step 8:

Get some natural sand and sift out larger stones and pebbles. Lay a drop cloth underneath the board section. Use a paintbrush to apply a mix of 3-1 wood glue to water over all areas that will be covered in sand. If you add too much water to the glue it will start to pool, making the sand look uneven. Add small pebbles along the base of the cliff. Pour sand over the glue and let it dry. Tip the board and tap the back to knock off loose sand. Fold the drop cloth and pour the extra sand back into your supply. Make sure to wipe off sand on the sides of the board. When the glue is completely dry use a large brush to sweep away any loose sand before painting.

Step 9: Painting

First paint in the deepest cracks with black paint with a small brush. Watering down the paint a little helps it flow into cracks. This is just to get the parts that will be hard to reach with a larger brush. We only used one 2oz bottle.
Next paint the base coat. We used one quart of light brown latex house paint. Paint everything, paint the sand, cliffs, sides of the board.
Dry brush the board with an off white. Maybe sure your bush has very little paint on it. Go slowly, make sure to dry brush the cliffs as well. You will need about 6 oz of paint for this step.
Next wash the cliffs with a dark brown paint. Make the wash thin enough that you can still see the white dry brush underneath it.
Wash the undersides or rocks and other areas that should be darker again.
Finally, lightly dry brush the most prominent rock edges with off white.