STAR DUSO: the Star Dust Sorter and Organiser

In a previous Instructable, we introduced a simple 3D-printed device designed to separate magnetic particles from dust collected from roofs or gutters. With a bit of luck, some of these particles might even be micrometeorites!

In this new Instructable, we present an updated version of the same device. Unlike the original model, the new design can handle a larger amount of dust by sorting magnetic particles into multiple collection areas. The device remains small and compact, making it easy to use together with a stereomicroscope for close observation.

1. 3D printer (using 1.4 mm PLA filament)
2. 2 mm transparent Perspex sheet
3. K-Knife or CNC laser cutter (for cutting the Perspex)
4. 4 × M2.5 machine screws
5. Small neodymium magnets (for magnetic separation)
6. Glue for plastic.

3D print the provided STL files.

We used a Creality Ender-5 Pro with a layer height of 0.2 mm, but any comparable 3D printer should work well.

The files to print are:

1. Bottom Ring (BottomRING.stl): secures the bottom Perspex disc to the middle ring.
2. Middle Ring (MidRING.stl): contains the 12 separation chambers.
3. Top Ring (TopRING.stl): combines with the top Perspex disc to create the rotating lid of the device.
4. Separation Ring (seprRING.stl): glued to the top Perspex disc to complete the magnetic separation chamber selection mechanism.

You’ll need to prepare two Perspex discs:

1. Bottom disc: 95 mm in diameter
2. Top disc: approximately 93 mm in diameter (it should fit snugly inside the upper ring)

You can order precisely cut Perspex discs online or make them yourself using a laser cutter.

For quick prototyping, I personally cut the discs using a K-Knife, carefully trimming the edges of a polygon with an increasing number of sides—until it became (almost) round!

1. Attach the bottom and middle rings:
2. Place the larger Perspex disc between the bottom ring and the middle ring, then fix the two rings together using four M2.5 screws.
3. Insert the selector ring:
4. Fit the selector ring into the central circular space of the middle (chamber) ring.
5. Prepare the top assembly:
6. Insert the second Perspex disc into the top ring.
7. Since the fit is designed to be snug, the disc should stay in place.
8. If it feels a bit loose, apply a small amount of glue along the inner edge to secure it.
9. Align and mark the top section:
10. Place the assembled lid on top of the middle chamber ring, aligning the screw holes carefully.
11. Using a fine marker, trace the contour of the selector ring onto the top Perspex disc.
12. Glue the selector ring:
13. Finally, glue the selector ring to the top Perspex disc, using the traced line as a guide for proper alignment (see last Figure).

Once the glue is completely dry, try fitting the lid assembly onto the middle chamber ring.

If assembled correctly, the lid should rotate freely, allowing you to align the opening of the central selector ring with the different separation chambers.

Open the lid and place a small dish in the center of the middle ring. This will help you load the device with the dust sample to be examined.

For this purpose, I reused a plastic cylinder from an empty roll of Scotch tape (Fig. A).

Its height keeps the dust concentrated in the center and helps minimize spilling into the separation chambers (Fig. B–C).

If you prefer, you can 3D print a custom cylinder or use any similar container that fits the central opening.

The dust sample shown in the figures and video was collected from the gutter of my house.

Once the sample is loaded, remove the cylinder (Fig. D) and cover the chamber with the ring lid (Fig. E).

The device is now ready for use (Fig. F).

Using a small neodymium magnet glued to the end of a stick or rod for easier handling, collect the magnetic dust from the central cavity of the device (Fig.A).

The particles will adhere to the upper Perspex disc as you move the magnet close to them (Fig.B).

Gently guide the magnet toward one of the collection chambers opened by the selector ring slit (Fig.C).

Once the magnet is inside the chamber, lift it slightly — the magnetic dust will detach and remain deposited within that chamber (Fig.D).

You can then rotate the lid to align the slit with a new chamber (Fig.E) and repeat the process to continue sorting the particles (see video picture).

The device is compact enough to fit under a stereomicroscope, allowing for detailed inspection and further separation of particles within the smaller chambers (Figure 1).

This fine separation can be done using small magnets attached to the end of a metal rod, or by opening the lid and manipulating the particles with pointed wooden sticks or tweezers (Figures 2).

To help prevent the selected particles from moving due to accidental vibrations or abrupt motions, you can drill small pits in the chamber floor. These tiny recesses act as traps to keep individual particles in place.

Using the stereomicroscope greatly aids in identifying and classifying the separated particles (Figure 3) and possibly spotting micrometeorites among them!

The STAR DUSO offers a simple, compact, and effective way to separate and study magnetic particles found in everyday dust. With a 3D printer, a few magnets, and some curiosity, you can build your own small laboratory for exploring cosmic dust right at home.

While not every magnetic grain will be a micrometeorite, the process of searching and examining these particles under the stereomicroscope is both educational and fascinating. I hope this project inspires you to look a little closer at the world around (and above) you.

If you build your own version or make improvements, I’d love to see your results and ideas shared in the comments!