The Prius rear hatch release switch is covered with some sort of black rubber that deteriorates with exposure to weather. Mine had gone through the usual phases of first getting sticky and gooey, leaving black yuck on my fingers every time I used it, to becoming so rigid that I could no longer operate the switch.
I took the whole thing apart and after about an hour of cleaning all the black rubber off the switch housing, modeled the housing and then created a model of the cover to fit. I printed it in TPU and it's been on the car for over a year and is still as flexible as the day I printed it, even when the temperature is below 0F. The print doesn't seal like the original part did, but a little silicone sealer added around the edges at install time takes care of that.
Please consider this for the Organizational Prize as it is posted on behalf of the Milwaukee Makerspace. Thanks!
Love this idea - I have a Prius with exactly the same problem. Just ordered a spool of TPU to give this a try. Thanks!