Luckily today's technology allows us to design and simulate idea's in a digital model, before constructing anything physical. This surely will save time and money.
Although this virtual environment has many advantages, it doesn't mean we cannot use "old" methods any more !
For me everything starts with a primitive sketch, on old-fashioned paper. Converting this sketch into a primitive 3D model, allows early evaluation of function, proportions, and so much more.
The 3D model can then be used as background for more detailed sketching, which in itself can be used again for more detailed 3D modelling. This process continues until the project converges to its final stage.