include <BOSL2/std.scad>

module cross(dim, a=CENTER, c=0, e=BOTTOM, t=0) {
    cuboid([dim[0], dim[1], dim[2]], anchor=a, chamfer=c, edges=e);
    cuboid([dim[1], dim[0], dim[2]], anchor=a, chamfer=c, edges=e);
    cuboid([dim[1]*2+2*t, dim[1]*2+2*t, dim[2]], anchor=a, chamfer=c, edges=e);
};

l = 100;
d = 6;
t = 1;

difference() {
    cross([l, d, d], a=BOTTOM);
    up(t) cross([l*2,d-2*t, d], a=BOTTOM, c=t, e=BOTTOM, t=t);
}