Thanks for testing updates jhagestad! I did notice some softening of the handle at really high temps (>500F) but nothing that would cause it to completely deform and fall off, but it got warm enough that mine fused to the rubber washer. It now one solid piece with the washer stuck to it but it still works and looks fine.
I might print a small batch this weekend and sell them at cost. 3D printing is still a very slow process, it takes about an hour to 3D print each handle. Painting them with several coats of paint and drying in between takes a couple of days at least. The material cost is not much, less than $1 for the washers and mounting hardware, but mainly time consuming.
What do WKC members think is a fair price? The handles can also be customized by adding initials or other short text to it. That just requires some tinkering with the CAD program.