I've always just built standard boxes where all of the joints are 90 degree angles. I'm gonna be building a box for my silverado tomorrow and it will be oddly shaped with miter cuts I think they're called. How do you join these type of cuts? It doesn't seem like you can screw them together.
Here's a pic of what I'm talking about
And also how do you measure the angles? Do you just guess and keep trying until it fits your car?