<craft>
    <parameter name="side1" type="int" default="3"/>
    <parameter name="side2" type="int" default="7"/>
    <parameter name="side3" type="int" default="5"/>
    <parameter name="width" type="int" default="10"/>

    <script type="text/openjscad">
        function main(params) {

        var length1, length2, length3, bar1, bar2, bar3;
        var width = params.width;

        var hinge = mathhinge(width*2);
        hinge = hinge.scale([0.5,0.5,0.5]);

            return hinge;

        } // end of main

        function mathhinge(width){

            var length = width; // Length of the complete hinge
            var height = 3; // Height (diameter) of the hinge
            var clearance = 0.4; // Clearance between cones and holes
            var gap = 0.5; // Clearance between hinge and sides

            // Parameters that the user does not get to specify
            var fn=24*1;
            var border = 2*1;
            var fudge = .01*1;          // to preserve mesh integrity
            var corner = 1*1;       // space between hinge and corner
            var hinge_radius = height/2;
            var cone_height = 1.7*hinge_radius;


            var hinge_module = hinge(hinge_radius, clearance, length, corner, cone_height, gap, fudge)
                                .translate([-hinge_radius,0,0])
                                .rotateY(90);

            var bar1 = bar(length, border, height)
                        .translate([0, hinge_radius+gap, 0]);
            var bar2 = bar(length, border, height)
                        .translate([0, -2*border-hinge_radius-gap, 0]);

            return union(hinge_module, bar1, bar2);

        }

        function hinge(hinge_radius, clearance,
                        length, corner, cone_height, gap, fudge){
            var rad = hinge_radius;
            var clr = clearance;
            var len = (length-2*corner)/3;
            var con = cone_height;

            // left outside hinge = (cylinder+box)-cone
            var outside = difference(
                            union(
                                cylinder({h:len-clr,r:rad})
                                    .translate([0,0,corner]),
                                cube([2*rad,rad+gap,len-clr])
                                    .translate([-rad,0,corner])
                                ),
                                cylinder({h:con,r1:0,r2:rad})
                                    .translate([0,0,corner+len-con-clr+fudge])
            )
            // inside hinge = cylinder+box+cone+cone
            var inside = union(
                            cylinder({h:len,r:rad})
                                .translate([0,0,corner+len]),
                            cube([2*rad,rad+gap,len])
                                .translate([-rad,-rad-gap,corner+len]),
                            cylinder({h:con,r1:0,r2:rad})
                                .translate([0,0,corner+len-con]),
                            cylinder({h:con,r1:rad,r2:0})
                                .translate([0,0,corner+2*len])
                            );

            // right outside hinge = (cylinder+box)-cone
            var right = union(
                            cylinder({h:len-clr,r:rad})
                                .translate([0,0,corner+2*len+clr]),
                            cube([2*rad,rad+gap,len-clr])
                                .translate([-rad,0,corner+2*len+clr])
                        );
                right = difference(
                            right,
                            cylinder({h:con,r1:rad,r2:0})
                                .translate([0,0,corner+2*len+clr-fudge])
                        );

            return union(outside, inside, right);
        }

        function bar(length, border, height){
            return cube([length,2*border,height]);
        }
    </script>
</craft>