Here's an interesting alternative to an established manufacturing solution.

CNC mills use spinning bits to remove material. This material comes off in the form of tiny chips. These chips must be evacuated, to avoid clogging the worksurface and potentially jamming or overheating the bit.

The common solution is to use a dust shoe, which encases the cutting area within a bristled perimeter while a vacuum theoretically evacuates the chips.

Image: ShopBot Tools

Image: AvidCNC

However, these simply aren't very effective, as the vacuum hose must be located a safe distance away from the spinning bit. Additionally, they obscure one's view of the cutting action, which may be required in order to make adjustments (or present video of the action, for content creators).

Some users get around the chip clearance problem by mounting air compressor attachments close to the bit, to continuously blow the cut out. But this presents additional hassles, from having to run the compressor and mount the fittings to the spindle/router.

Image: Community Carbide 3D

Image: 1000DIY

A clever, low-tech solution has emerged. People have been 3D-printing their own collet fans:

Image: Bryan_81523

These are essentially impellers, designed to snap onto the collet nut with a friction fit.

Image: Durahl_135319

Image: Greenwood Designs

As the bit spins, the fan creates enough downdraft to blow the chips out of the cut.

Image: Saur0n

There are, however, two things to be mindful of. One, the fan's design must be robust enough that the thing doesn't come apart at high rpms.

The second potential hazard relates to a risk CNC mill operators are already aware of: Accidentally running the spindle into a jig or clamping fixture used to hold the workpiece. The collet fan's wider diameter creates a larger "danger zone" around the bit. CNC enthusiast Bryan Howard demonstrates a collet fan collision in slow-mo, with the spindle running at 24,000 rpm:

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Obviously, using a collet fan behind a protective enclosure is recommended.