One of those products that is so useful that you wonder why you didn't think of it yourself--a cap for the actuator of a stomp switch. Three Allen screws hold the button in place, providing more surface area, increasing comfort and accuracy and reducing missed hits. These are the maker's Version 1 for standard 3/8" (10mm) actuators. Available in multiple colors of anodized aluminum or clear acrylic, each comes with an Allen wrench.
BTW: Unlike the cheaper clones, these won't break and will stay in place.