OpenJSSCAD X/Y calibration object

gistfile1.js

// - Set nozzle diameter and layer height below
// - Print with no top/bottom, one shell, same layer height

var nozzle = 0.35,
    layer = 0.2;
function fence(side) {
    var inside=side-10-nozzle,
        outside=side+nozzle;
   return cube([outside,outside,0.2])
    .center([true,true,false])
    .subtract(
        cube([inside,inside,20])
        .center([true,true,false]))
    ;

}

function main() {
    var list=[];
    for(var i=20; i<=80; i+=20) {
        list.push(i);
    }
    return union(list.map(function (side) {
        return fence(side);
    }));
}