If you're like me you've had your fender liners out and in a few times and the clips are pretty trashed, cracked, split, don't hold, etc or are just plain missing.
I found that M5 rivet nuts fit into the holes that the clips used to go into, on the fenders and the body of the car as well. I bought M5 bolts and M5 washers and replaced my clips with them.
I bought the cheapest rivet nut tool that came with an assortment of aluminum M5 rivet nuts on eBay for about $30. Aluminum rivet nuts are easier to pull into place and won't rust. It's an easy project that lets you remove and install the fender liner an endless number of times without the clips failing. You can do colors if you'd like, I picked red to go with my black car. I've gotten a few positive comments but mostly they go unnoticed.
There's two different styles available depending on how much color you want to show, I prefer the flatter ones but some may like the more pronounced style.
This should work for most Toyota over a wide range of years and probably on other places where there's push clips like bumpers and decorative engine covers. I don't know how durable the red anodized washers will be, but they survived a road trip from Chicago to Tail of the Dragon, driving around on the Dragon, and back to Chicago without any apparent harm so they're not as fragile as I'd thought they would be.