About this 3D model

module carrito() { $fn = 90; rotate(270, [0, 1, 0]) translate ([12.5,0,-25]) difference (){ //beginning og difference 2 union (){ //beginning of union 1 difference (){ //beginning of difference 1 //main cube translate ([-12.5,-55,-2]) cube ([12.5,110,52]); //hueco pa caja de bolas IZQUIERDA translate ([-13,-40,35]) rotate(90, [0, 1, 0]) cylinder (h=7,r=11); translate ([-13,-40,35]) rotate(90, [0, 1, 0]) cylinder (h=20,r=9.5); //hueco pa caja de bolas DERECHA translate ([-13,40,35]) rotate(90, [0, 1, 0]) cylinder (h=7,r=11); translate ([-13,40,35]) rotate(90, [0, 1, 0]) cylinder (h=20,r=9.5); //lineal rollers translate ([0,40,0]) cylinder(h = 24, r= 7.5); translate ([0,-40,0]) cylinder(h = 24, r= 7.5); //passthrough roller holes translate ([0,40,-2]) cylinder(h = 60, r= 5); translate ([0,-40,-2]) cylinder(h = 60, r= 5); //ziptie holes left translate ([-12.5,-52,3]) cube ([12.5,2,5]); translate ([-12.5,-52,16]) cube ([12.5,2,5]); translate ([-12.5,-30,3]) cube ([12.5,2,5]); translate ([-12.5,-30,16]) cube ([12.5,2,5]); //ziptie holes right translate ([-12.5,50,3]) cube ([12.5,2,5]); translate ([-12.5,50,16]) cube ([12.5,2,5]); translate ([-12.5,28,3]) cube ([12.5,2,5]); translate ([-12.5,28,16]) cube ([12.5,2,5]); //center square hole; //translate ([-12.5,-25,30]) //cube ([12.5,50,20]); //apretador de caja de bola IZQUIERDA translate ([-13,-41,40]) cube ([12.5,2,10]); translate ([-12.5,-25,40]) cube ([12.5,5,10]); //apretador de caja de bola DERECHA translate ([-13,39,40]) cube ([12.5,2,10]); translate ([-12.5,20,40]) cube ([12.5,5,10]); //tornillo de apretar la caja de bola translate ([-9,56,47.5]) rotate(90, [1,0,0]) cylinder (h=112,r=1.5); } //end of difference 1 translate ([0,-20,-2]) cube ([12.5,40,52]); } //end of union 1 //CENTER SCREW 11mm NUT MOUNT TOP cylinder(h = 60, r= 6); translate ([0,0,-2]) rotate(90, [0, 0, 1]) cylinder (h=38,r=11,$fn=6); //CENTER SCREW 11mm NUT MOUNT BOTTOM translate ([0,0,40]) rotate(90, [0, 0, 1]) cylinder (h=10,r=11.05,$fn=6); //side center cut IZQUIERDA translate ([12.5,-20,-2]) rotate (60,[0,0,1]) cylinder (h=52,r=11.05,$fn=3); //side center cut DERECHA translate ([12.5,20,-2]) rotate (60,[0,0,1]) cylinder (h=52,r=11,$fn=3); } //end of difference 2 } carrito();