$fn = 200;

w = 1;
h = 1;

function fn(a, b) = round(sqrt(pow(a[0]-b[0],2) + (pow(a[1]-b[1], 2))));

module shape(i) cylinder(h, max(w/2*((i^2.1)*0.01),0.5), max(w/2*((i^2.1)*0.01),0.5), $fn=12);

function b_pts(pts, n, idx) =
    len(pts)>2 ?
        b_pts([for(i=[0:len(pts)-2])pts[i]], n, idx) * n*idx
            + b_pts([for(i=[1:len(pts)-1])pts[i]], n, idx) * (1-n*idx)
        : pts[0] * n*idx
            + pts[1] * (1-n*idx);

module b_curve(pts)
    let (idx=fn(pts[0], pts[len(pts)-1]), n = 1/idx) {
        for (i= [0:idx-1])
        hull(){
	  translate(b_pts(pts, n, i)) shape(i); // change i to 1 for constant with
           translate(b_pts(pts, n, i+1)) shape(i); // change i to 1 for constant with
    };
}

module spike() {
  polygon([[0, 0], [10, 0], [5, 50]]);
}

blade = 8;

module fan() {
    for (i = [0 : blade]){
        rotate( i * 360/blade, [0, 0, 1])
        b_curve([[0, 0], [20, 30], [10, 45], [0, 37]]);
    }

    cylinder(h, d = 35);
}

difference() {
    fan();
    cylinder(h, d = 5);
};