Extruder movements on both MK2/S and MK3 can be quite difficult to see. The other three axes are easily visible, and honestly, it can be super mesmerizing to watch. A lot of us always want to know what’s our printer doing. Peter Roodenburg designed the Dutch Windmill motor rotation indicator, and we immediately fell in love with it.

His design is super simple, all you’ll need is:

  1. Super Glue
  2. 8×3 mm rare earth magnet (neodymium magnet)
  3. 3D printed visualizer

When you have the print done, just glue the magnet to it using a good amount of superglue. Let the glue dry for a minute. Then you’re ready to attach the indicator to the extruder motor axis. It’s made from metal, so the magnet will stick to it and rotate whenever the axis rotates. The indicators fit both MK2 and MK3 as they use the same stepper motors and will probably fit other stepper motors with a similar design.

We designed some more of these indicators so you have more options to choose. You can also create your designs, these are really simple to make. The only dimension you should keep in mind is the circular opening in the stepper motor, which is 8.5 mm in diameter. And to make it look even cooler, you can use the color print feature of PrusaSlicer. Read the tutorial for that.

The circle, cloverleaf, Prusa, triangle and Peter’s windmill extruder visualizers

Even though these rotation indicators are mostly just for a cool look, they can be surprisingly handy when you’re dealing with a jammed extruder, overtightened idler or playing with retraction settings. You’ll be able to tell what’s the extruder doing at all times.

Magnet sizes and where to buy them

You’ll need  8×3 mm (~5/16″ x 1/8″) rare earth magnets. You can also stack thinner magnets if you do not have 3mm thick ones (stack three 1mm thick magnets on top of each other). Smaller diameter magnets did not reliably work for us during testing. You can get them from eBay, Amazon, Aliexpress or your local supplier.