No, I'm not talking about the build volume of 1 kg of filament. (Although with low-infill, you should be able to print a full-sized loaf. )
Instead, I'm talking about the growing excitement over at-home production of filament, either from virgin plastic pellets or from recycled plastic scraps. The basic motivation for that is to save money. The common refrain goes something like this: "commercial filament is $50/kg, when pellets are $5/kg. And if you recycle your plastic from milk jugs, it's even free!"
The idea has been around for a while, but the excitement really kicked off when the Filabot guys ran a successful kickstarter. There was even a $40,000 "X-prize" by the Kauffman Foundation to design a low-cost at-home filament extruder, which Hugh Lyman won with his design. There are plenty of others that are now offering similar machines.
When I started this business of distributing high-quality 3D printing filament, people asked me why I'd want to do that when people can make their own. This is where the bread analogy comes in.
Anyone could make bread at home. If you are methodical, you can make a pretty good loaf of bread for about 30 cents. You don't even have to do most of the work. You can buy a nice breadmaking machine for about $100 and, as long as you stick to a working recipie, you'll get a consistent result each and every time. And, after about 30 loaves, you've broken even!
My mom had a breadmaker. It pumped out really good loaves of bread. A couple times, though, my mom forgot something in the mix, or tried to be creative - and the result was not so good or outright failures. Then, there was the need to get the machine out, load it, and then clean up afterwards. (With extruding plastic, at least you don't have to wash everything!) Eventually the machine stopped working, and she didn't bother getting a new one. At home baking is not what put Wonder Bread out of business. People still buy the $3 loaf of bread because it's convenient, and consistent.
Unless you are an experimenter, or have particular needs for custom formulations, you probably would rather buy a good roll of filament and get on with the printing. I want to sell the Oroweat of filament - great quality, at a somewhat higher price than the bargain filament. Once you try the quality of our filament, I think you'll agree.