Well done Jasper!
Although I have been working in automation for the past 6-7 years, I spent the previous 25 years in product development for the injection moulding and prototype industries.
During that previous life, I frequently . . . as in several times per week, met people who were disappointed to learn about the cost and complexity of even low-volume injection moulding.
However as Jasper has so well illustrated, and a few others have suggested; there are some alternatives that work well for low volume requirements.
Possible manufacturing methods for the production of low volume enclosures:
? Fabrication (cutting and gluing) from flat stock . . . best for very low production runs
? Additive fabrication using various rapid prototyping methods (SLA, SLS, RepRap, MakerBot, etc.) . . . also best used for very low production runs
? Machining from solid blocks . . . depending upon the complexity of the enclosure, material selection and production volumes, CNC machining can sometimes be a cost effective method
? Casting using simple moulds (usually RTV moulds cast from master models produced by fabrication and/or machining). Today there is a wide assortment of both casting resins (acrylics and urethanes primarily) and RTV (Room Temperature Vulcanizing) materials
? Low volume injection moulding from soft tooling. Soft tooling ranges from aluminum reinforced cast tooling epoxies (not recommended) to temporary aluminum cores and cavities.
? Custom machining of OTS (Off The Shelf) enclosures . . . many enclosure manufacturers offer custom machining, painting, membrane switches, Lamacoid services, etc; to help create a custom look
? Unfortunately, vacuum forming sheet stock over temporary or permanent moulds is frequently overlooked; however from the standpoint of tooling cost, tooling delivery, part cost and design freedom this method has a lot to offer . . . most notably in large enclosures
At any rate it is important to understand, that like any engineering endeavor there are some compromises that are required. Most notably, every one of the above manufacturing methods placing unique technical requirements related to product design (form), material properties and performance.
It is not enough to draw an interesting shape and then go shopping for the cheapest price. The first step is to establish the production quantities; product price point and delivery time to market . . . these factors will be the largest influence on what manufacturing method will be best suited to the project.
Once the quantities, price and production method have been established, then the product can be designed . . . taking into account the limitations of material selection, wall thickness, corner radii, mounting bosses, cooling slots, etc. required by the chosen manufacturing method.
Mike Mc, unfortunately all of my contacts from the industry are on the other side of the big pond so I cannot make any recommendations regarding suppliers, but I would think that there would be some businesses in the UK that could do the work. Usually it is best to do this kind of work locally as issues can be resolved more easily than if you are working long distance.
