The leading electronic component suppliers hold stocks of literally thousands of various types of enclosures so there is little point in paying for the tooling costs necessary to manufacture your own custom designed enclosure.
Nor is it necessary to go overseas for a supplier. Many of the companies that manufacture and supply enclosures are British. The ones we use are more than helpful in providing whatever information we require for a new design. Clearly, they know that there may be sale in it for them. Crucially, stock enclosures come with datasheets and drawings provided as DXF files.
So at the outset of your project, consider the nature of the enclosure required, and start searching for suitable stock enclosures. For lowest cost production, consider single board configurations with as many surface mounted parts as possible. This will minimise hand assembly processes and make local UK manufacture competitive and economic. For lowest cost, the PCB should be assembled on automated pick and place assembly lines and ‘clicked’ into an enclosure, barely touched by hands.
Let’s consider the PCB design process. The mechanical design of the PCB must be matched to the enclosure selected. So the enclosure DXF files must be imported into the PCB CAD layout software right at the start of the PCB layout process. The PCB layout is then generated around this mechanical drawing.
Performing both the PCB layout and the mechanical design at the same time achieves excellent dimensional accuracy. Mounting holes or spigots will line up. Connectors will fit through the enclosure. LEDs will line with associated apertures. Should the enclosure require any silk-screened graphics, this can be designed and aligned at the same time.
A stock enclosure will almost certainly need customising to your requirements. The enclosure suppliers may offer to machine do the machining for you. All engineering subcontractors will program their milling machines from DXF files which your PCB CAD layout software should be able to output. The photography for the silk-screening of the enclosure can be produced from Gerber or HPGL format files.
Whilst the enclosure company is machining and silk-screening the enclosures, the PCB can be manufactured at the same time. When the two come together they should fit perfectly.
With a little careful planning, very professional results can be produced at low cost, even for small runs.