length = 116.0;
width = 10;
height = 20;

peg_width = 2;
how_many_pegs = 16.0;
peg_height = 12;

union(){
  cube([length, width, height-peg_height]);
  for ( i = [0:how_many_pegs] ) {
    translate([i*(length-peg_width)/how_many_pegs, 0, height - peg_height])
      cube([peg_width, width, peg_height]);
  }
}

echo((length-peg_width)/how_many_pegs);
echo((length-peg_width)/how_many_pegs - peg_width);