I came up with an idea for a universal fitting and air hose to supply air to my engines that was convenient to use and was not bulky and looked good.
I used a Iwata air brush hose I purchased from my local hobby / craft store and figured out what thread and shape I needed to make a fitting to match the hose.
The part that fits the engine can be made to what works best for that particular model.
I'm not sure, but I would think this hose thread would be universal to other air brush models.
Attached picture of fitting dimensions.