When airbrushing with my cheap timbertech airbrush my index finger started to hurt after a while pressing down the action trigger.

So I designed a simple knob which has a bigger and rougher surface so I could spray without hurting fingers afterwards.

printing is straight forward. Just use 0.16 height setting. Should fit snuggly on the timbertech. If need be you can use a double sided tape to stick it to the knob.