Draw mesmerizing geometric patterns — tweak the gears and watch the curves bloom.
A spirograph turns a couple of numbers into astonishingly intricate patterns. It recreates the classic toy — a small gear rolling inside a larger ring, with a pen poked through a hole — but with sliders instead of plastic. Change the size of the ring, the size of the rolling gear, and how far the pen sits from the gear's centre, and the curve transforms: loops multiply, petals bloom, stars sharpen. Watch each pattern draw itself in a sweep of colour.
Behind the beauty is a single elegant equation (a hypotrochoid), evaluated point by point on a canvas in your browser. Nothing is uploaded, there's nothing to install, and you can download any pattern you like as an image. It's equal parts maths demo, art toy, and quiet time-sink.