It can be used to repair other things as well and works on aluminum, steel, ceramics, glass, wood and some fabrics. It's waterproof, UV-resistant, electrically insulating, and dishwasher-proof when cured. You can blend different colors together to create your own custom color.
Promising review: "I have an older GE Dryer that somehow cracked the plastic on part of the exhaust vent assembly. This was causing things to get caught in the hole as well as sucking air and lint into the dryer without going through the filter, ugh. Unfortunately, this was a large plastic part and a replacement cost $80, which is an awful lot to spend on a 10-plus-year-old dryer. I purchased Sugru on a recommendation and used it to patch up the hole in the dryer and after maybe 50 loads, it has held up perfectly. Nothing gets snagged now, and it even looks reasonably decent. Definitely recommend this stuff!" —Chad Cunningham
Get a three-pack in assorted colors from Amazon (red, white, and black) for $10.