Developed by some very nerdy chaps deep in the bowels of Madison, WI, the product is basically a high metal content 3D printing filament, which can run on just about any cheap printer anywhere. The key point to note is that it’s not expensive, doesn’t require an expensive printer, and yet can produce stunning results which go way beyond standard ABS or PLA plastic output.
— Nigel is the managing editor of the Red Ferret, and freelance columnist for the Sunday Times newspaper in London.

Some History on The Virtual Foundry

What is The Virtual Foundry? Essentially it's the quest to create high quality metal 3D prints without requiring a complete, high-end, metals studio. This quest actually started well before 3D printing became a viable option. Earlier versions relied on combinations of cold casting and electroforming. Using these techniques we were able to create some striking copper objects. When 3D printing came into our lives, our first thought was that if it can't print metal, it has relatively little value. So began our 3 year quest to develop a product that would let any desktop 3D printer create pure metal output. After some early successes with high levels of metal infusion, we were able to produce about 20 pounds of what we now call Filamet™. This was enough to print some prototypes and develop a proof of concept. From here we looked to Crowdfunding as a way of bringing this development to market, launching a successful Kickstarter campaign which raised about 135% of our target funding goal. 

This put our move from prototype to production into motion. Our early intent was to contract out manufacturing. After a series of meetings we concluded that we were not going to be able to find a vendor willing to put our secret recipe of exotic materials through their multi-million dollar plastics equipment. After this conclusion we set out to design our own system. We bought a 40 horsepower single screw extruder. Since there was really no product like this on the market, existing handling equipment just wasn't quite up to the job. Over the year following our Kickstarter we designed and custom built all of our own processing equipment. Being of the Maker generation, we wound up with a set of custom machinery that can create product at a pace that exceeds our most aggressive estimates. For the nerds, all of our custom equipment is run by micro-controllers, some PIC's, mostly Arduino.

So, today, we are manufacturing high quality, high purity, 3D printing filament. We keep improving this number, but our current products are running at 90% metal. We consider the theoretical maximum metal content to be in the neighborhood of 95%.

Engineers at Lockheed-Martin say we have found the Holy Grail of 3D printing; Pure metal prints from existing desktop printing hardware. It’s quick, it’s painless, and most importantly it leaves you with a 3D printed object made entirely of high-purity metal.
— Bradley Woods, The Virtual Foundry