I laser cut and 3D print. No matter how well I think my designs and plans are, it still takes a few tries to get it right. And then I still have second thoughts...
As to bridge or elevated structures, I try not to use girders but instead to use open trusses because girders block views and trusses are open. I like to see the trains moving beyond the truss-shapes.
Here is a 5-track truss bascule.
