Once the product specifications are defined, the design process starts, at the end of which there will be a well defined concept of the end product.
This process starts with the selection of the larger, protruding, or visible components, such as relays, switches, connectors, displays etc. Then we aproximate the location of these components by factoring in user experience, optimized circuit layout, ease of assembly and visual aspect. At the completion of this phase we have a good understanding of the device's price at the actual production, size and feel, and the whole manufacturing process that is still ahead.
At this phase we make a sketch of the device where the visible features are all in their places and can be changed, moved, removed or others added without much problem.