// SignWave shaped hill

    Xamp  = 50; // one wave length
    Yamp  = 50; // one wave length
    Zamp  = 20; // amplitude (height)

    delta = 0.5; // ste
    cycle = 1;  // count of waveform

    module SignWaveHill(Xamp, Yamp, Zamp, cycle,  delta) {
    X2 = Xamp/2;
    Y2 = Yamp/2;
        for (        x = [-X2:delta:X2] ){
		for (y = [-Y2:delta:Y2] ){
		 amp = Zamp * cos(cycle/2 * (y / Y2) * 360.0);
                   hull(){
		   z = amp * cos(cycle/2 * (x / X2) * 360.0);
		      translate([x, y, Zamp]){
                      cube([delta, delta, z + Zamp ]);
                      }
                   g = amp * cos(cycle/2  * ((x - delta) / X2) * 360.0);
		      translate([x - delta, y, Zamp]){
                      cube([delta, delta, g + Zamp]);
                }
            }
        }
    }
    }
    
// uncomment gives  3 x 3 cycles    
//     for (x = [-1:1:1] ){
//           for (y = [-1:1:1] ){
//               translate([ x * width * 2, y * length * 2, 0])
		     SignWaveHill(Xamp, Yamp, Zamp, cycle, delta);
//           }
//       }