I lost one of the knobs that came with my Camp Chef Everest x2, and drew up a model that is ALMOST identical to the real knob. The knob fits 6mm grill knob axles with a 1mm flat. The part is designed to print with supports.

Here's the onshape link for modification: https://cad.onshape.com/documents/8b91a9654cd7c81fd354115b/w/90d9c36b549b40f2af051c3f/e/4bfb0e7505d1a17ea081ccb4?renderMode=0&uiState=68bd7572e12e0deaa44ceac6