This is a co-axial air assist for the LaserSaur laser cutter that I turned from some 6061 Aluminum round stock.
I've provieded the original Solidworks files and .step. The air inlet connector is from McMaster Carr for 1/4" tube, but any quick-connect with 10-32 threads will work. The coiled 1/4" tubing is also from McMaster. It's lashed to the back rail of the 'saur with zip-ties and run out of the enclosure with 1/4" Swagelok bulkhead fittings and eventually meets up with an air compressor and regulator.
The airflow requirements are pretty minimal, so 1/8" tubing could also be used and would bend easier. A 1/8 - 1/4" adapter would be needed then to use the coiled tubing.