union() {
    difference(){
        translate([0,0,0.4]) cube([50,50,4.6]);
        translate([0,0,4]) linear_extrude(height=2) import("../graphics/arms.dxf");
        translate([2,38,4]) linear_extrude(height=2) scale(0.2) import("../graphics/arms.dxf");
        }
    cube([24.5,24.5,1]);
    translate([25.5,0,0]) cube([24.5,24.5,1]);
    translate([0,25.5,0]) cube([24.5,24.5,1]);
    translate([25.5,25.5,0]) cube([24.5,24.5,1]);
}