Mix the almonds, pecans, and walnuts in a small bowl and set them aside. Place the white sugar, brown sugar, and salt in a 10" nonstick skillet, mix well until combined. Add the corn syrup and turn the heat to medium high.
When the mixture begins to bubble, about 1 minute, stir well for a couple minutes to combine the corn syrup and completely dissolve the sugars.
Add the mixed nuts and stir constantly for 1-2 minutes, until all liquid is absorbed and the nuts are well coated. Move to a clean dish.
When the nuts are cool enough to handle, separate the clumps, and allow them to dry for a couple hours. They will still retain their sticky surface, and you'lll have to pry them off the dish. But that's half the fun!