2.5 in OD magnetic hose couplings. Compatible with standard 2.5" dust collection hoses. There are a few designs out there, but I couldn't find one with 2.5" dia and decided to make my own. the 2.5" one uses six 8mm x 3mm ones

Print Settings

Printer brand:

Creality

Printer:

Ender-3 v2

Rafts:

Supports:

Resolution:

.20

Infill:

35 gyroid

Filament brand:

Generic

Filament color:

Yellow and Red

Filament material:

PLA

Notes:

3mm walls - To increase rigidity

I also have Jerk/Acceleration control and Z hop setup on my printer, but this is not necessary.

You'll need to introduce a pause in your printing to embed the magnets in the print. See the section below on pausing for more details.

Pause to insert magnets

Inserting the pause:

In the slicer, you'll need to insert a pause in the G-code at the appropriate height/layer depending on your layer height. You want to pause right before the layer where the magnet cavities are sealed over.

Depending on your printer, slicer, and controller application, the process to insert a pause and resume from it might be different. I used Cura (5.6.0) and Octoprint, so here's what I did to add the pause:

Slice in Cura using the normal print settings above but do not save, instead select "Preview".

Find the topmost layer before the magnet cavities are sealed using the slider on the right. For the 2.5" model and 0.2mm layer height, this was layer #20. (see pic)

From the top menu bar, select Extensions->Post Processing->Modify G-Code.

Click on "Add a script" and select "Pause at height"

Edit the Pause Layer, Method, and other settings and close. (see pic)

Adding the script will void the slice, so you'll need to re-slice and save the final G-code.

Embedding the magnets:

If the pause was set up correctly, the printer should have paused at the right layer with the print head safely out of the way. You want to make sure that the print bed continues to be heated to avoid the print moving off the bed.

The magnets need to be placed such that their polarity is alternated. This will allow two such prints to attach to form the coupling.

Some tips -

IMPORTANT! Make sure the polarities are alternated!

The cavities are snug by design. I like to place the magnet flat right next to the cavity and quickly slide it in with a fingertip.

My print head doesn't have any ferrous parts that would cause the magnets to jump out of the print and attach to something else. If yours does, you might want to use some superglue to fix the magnets before resuming the print.

Carefully seat the magnets so that the top surface is flush with or slightly below the top layer of the rest of the print. If you use too much force to push down on the magnets, you might mess up the print bed leveling and cause the subsequent layers to not adhere. I've had success with a couple of magnets slightly protruding above the top layer as well... subsequent layers will hide them.

If the cavities are too snug for your magnets, you could try printing bigger - at 105% perhaps.

Once you've placed all the magnets and ensured that the polarities are alternated, you can resume the print. (From Octoprint, in my case)

2.5-in-magnetic-dust-collection-hose-coupling

0.2mm layer, 2 walls, 15% infill