I believe that in the near to mid-term the financial and societal impact will be with things like the Optomec Aerosol Jet which is starting to print superior electronics and solar cells or large scale self assembly can create superior products that are pushing beyond existing lithography.
These machines and capabilities are in the million dollar per machine to many millions of dollar for a facility range. However, the value in being to push the frontier and make superior electronics and computers is where more value and impact is being created. The Optomec is able to turn carbon nanotubes into 5Ghz electronics or make solar cells with 20% efficiency. They are still working out volume production.
Also, more useful than a $5000 desktop manufacturing device is a membership to something like Techshop for $120-150/month.
TechShop provides you with access to a wide variety of machinery and tools, including milling machines and lathes, welding stations and a CNC plasma cutter, sheet metal working equipment, drill presses and band saws, industrial sewing machines, hand tools, plastic and wood working equipment including a 4' x 8' ShopBot CNC router, electronics design and fabrication facilities, Epilog laser cutters, tubing and metal bending machines, a Dimension SST 3-D printer, electrical supplies and tools, and pretty much everything you'd ever need to make just about anything.
The small 3D desktop machines can make crude electronics but there is a limited need for crude electronics and there is competition for electronics that are mass produced but configurable (FPGA, EProm etc...) or customizable. As the capabilities of the cheap desktop machines grows then they will have more of a role but there cannot be too much sacrifice of quality by going cheaper.
The analogy is less like desktop PCs versus Mainframes to hand weights versus a gym membership to 24 Hour Fitness. Building things now for most people and companies it is better to get professional range of equipment and have trainers guiding and teaching to get a top quality result.
There will need to be a killer app to make the small 3D desktop manufacturing machines take-off. The PCs had the Lotus 1-2-3 and Excel spreadsheets and word processors that provided value and a reason to have Personal Computers. When making physical products, they have to compete with mass produced products. How much does personal customization make a difference and is better than a service bureau that provides customization ?
The 3D personal manufacturing capability becomes liberating and game changing when
1. It is able to use raw materials from the environment or the operating costs become so low that it beats buying from stores.
2. The convenience and responsiveness of using it makes it better and any trade-off in quality or function is not a problem.
Possible Killer Apps for 3D Personal Manufacturing
1. Able to make car parts or replacements for other home or business products that are worth $1000+/year
2. Able to make things to fix or improve real estate. Something that goes beyond what is currently at Home Depot and Lowes.
3. Able to make products to improve health and lower health costs. Medical test devices and personal aid products and devices.
4. Make energy generation devices that are lower cost than what can be bought. Make and deploy solar cells and the wiring or have wireless energy transmission.
A well stocked Techshop facility or fabrication service bureau should enable the applications first, because larger and more capable fabrication devices should be enable the individual or small company to make more things first.
There are many other killer apps and pathways but it either has to be valuable new capability, money/business generation or reducing a substantial current cost. Making cheaper cups and bowls or cheap electronics is not a substantial cost or value in most cases. Those are niches, but not something that would generate a mass market.