k = 3;
pi = 3.14159;

// 3D line parameters
smooth = 10; // line smoothing - WARNING: increasing this value too much causes the compilation to take a long time.
line_w = 0.2; // line width

////////////////////////////////////////
// FUNCTIONS
function CinquefoilKnot(k, u) = let(
    x = cos(u)*(2 - cos(2* u/(2*k + 1))),
    y = sin(u)*(2 - cos(2* u/(2*k + 1))),
    z = -sin(2* u/(2*k + 1))
) [x, y, z];

function getPoints() = [
    for (u = [0:2:360*(k*4)])
        CinquefoilKnot(k, u)    
];

///////////////////////////////////
// MODULES

module line(start, end){
    hull() {
        translate(start) sphere(r=line_w, $fn=smooth);
        translate(end) sphere(r=line_w, $fn=smooth);
    }
}
module poly3Dline(points, index){
    if(index < len(points)){
        line(points[index - 1], points[index]);
        poly3Dline(points, index + 1);
    }
}

////////////////////////////////////////
// TEST

scale(5)
poly3Dline(getPoints(), 1);