Air Flow Indicator

Air Flow Indicator using a thin wall cylinder with a 1.5° taper outwards towards the top.

During printing, you just need to drop a 6mm airsoft bb down the middle. The holes are perfect for 6mm OD PVC tubing, they are undersized by 0.2mm. Use some Oil when seating the hose in the openings to make insertion easier.

If you have a way to calibrate it, it can even be used to measure airflow.

It just needs to be printed with a transparent or translucent filament, even PLA works in terms of clearness. For less transparent materials, consider printing the round version, it has only one wall which makes the bb easier to see.

For a given airflow, assuming it is in the measurable range, the readouts on my test print were surprisingly consistent. The conical section is 60mm long, which should allow for a fairly precise readout of the flow. I used a 0.23 gram 6mm bb to measure the air output of a former A/C compressor.