Monopatin

//!OpenSCAD

difference() {
  union(){
    cube([80, 50, 15], center=false);
    translate([0, 25, 0]){
      cylinder(r1=25, r2=25, h=15, center=false);
    }
    translate([80, 25, 0]){
      cylinder(r1=25, r2=25, h=15, center=false);
    }
  }

  union(){
    translate([0, 5, 0]){
      cube([80, 40, 10], center=false);
    }
    translate([0, 25, 0]){
      cylinder(r1=20, r2=20, h=10, center=false);
    }
    translate([80, 25, 0]){
      cylinder(r1=20, r2=20, h=10, center=false);
    }
  }
  translate([10, 50, 5]){
    rotate([90, 0, 0]){
      {
        $fn=50;    //set sides to 50
        cylinder(r1=1.8, r2=1.8, h=60, center=false);
      }
    }
  }
  translate([70, 50, 5]){
    rotate([90, 0, 0]){
      {
        $fn=50;    //set sides to 50
        cylinder(r1=1.8, r2=1.8, h=60, center=false);
      }
    }
  }
}
translate([50, -50, 0]){
  difference() {
    cylinder(r1=25, r2=25, h=5, center=false);

    cylinder(r1=4, r2=4, h=20, center=false);
  }
}
translate([0, -50, 0]){
  difference() {
    cylinder(r1=25, r2=25, h=5, center=false);

    cylinder(r1=4, r2=4, h=20, center=false);
  }
}
translate([-50, 0, 0]){
  difference() {
    cylinder(r1=25, r2=25, h=5, center=false);

    cylinder(r1=4, r2=4, h=20, center=false);
  }
}
translate([-50, -50, 0]){
  difference() {
    cylinder(r1=25, r2=25, h=5, center=false);

    cylinder(r1=4, r2=4, h=20, center=false);
  }
}