If you mean fenders, nuts and bolts work the best. If you use the nylon cored locking nuts, you don't need to apply forces strong enough to crack the fenders, and they will still be tight.
Elliott & Vicky, and Sadie the GSD copilot
2014 36RE, Onan, Titan disc brakes, 17.5 inch Sailun H tires, lots of other options
2013 RAM 3500 CC, LB, DRW, Cummins, AISIN, 4x4