They say waiting to get something is often more enjoyable than actually getting it.

That's not how Jeff Bezos sees it. In the last few years, the founder has been in relentless pursuit of a lag-less future, one where you barely have enough time to utter the word "shipping" before your package arrives. In this utopia, deliveries take place in a matter of hours, not days. To make it a reality, Bezos is bringing the full power of Amazon's supply-chain resources to bear. The company has plowed nearly $13.9 billion since 2010 into new warehouses near its customers. It's an undertaking only a massive multinational would dare attempt.

But a handful of smaller companies are convinced there's a way to get products to consumers just as quickly, with greater satisfaction and at a fraction of the overall cost. The future, these companies argue, is in on-demand 3D printing.

These two ways of delivering goods couldn't be more different. One relies on scaling and infrastructure to reduce transportation time. The other eliminates as much infrastructure as possible and instead sinks money into materials and on-site manufacturing. Yet both share a common dream: achieving a just-in-timeness never before seen in the history of commerce.

It won't be long before these technologies start overlapping and interacting — and that's a good thing. The resulting combinations will iron out a lot of the inefficiencies of using either method alone. But however it happens, it probably won't be hailed as a "3D printing revolution" or as a "shipping revolution." It might simply be known as the just-in-time revolution.

The race to 'instant'

Amazon is merely one of a growing number of businesses all jockeying to see who can shave the most delay off of their shipping options. Recently, eBay and WalMart both began testing same-day delivery in parts of the country. The competition to eliminate just a few extra shipping hours is intense; to get deliveries to customers in under an hour, eBay dispatches college students by foot, bike and taxi to pick up products at local big-box stores and bring them to people's doorsteps.

Faster shipping is costly. As a share of Amazon's total sales, the amount of money that went to shipping came to nearly 5 percent in 2011, up from just 3.2 percent in 2009. Shipping is increasingly eating into Amazon's profits, and the move to same-day delivery promises to exacerbate that trend.

Amazon is moving ahead anyway. By bundling same-day delivery with Amazon Prime — whose members spend up to twice as much as non-members, according to some estimates — the company is likely to make up for any shipping-related shortfalls. It's hard to see a mom-and-pop store pulling off a feat like this; only a company as large and coordinated as Amazon has the means to use same-day shipping as a loss-leader.

But same-day shipping doesn't solve everything. It raises the pressure on Amazon to have an even more reliable inventory than it does now, lest an order come in and can't be fulfilled within 24 hours.

The business case for 3D printing

Faster shipping has also played an important role behind the scenes, allowing companies to produce a wider variety of products with less unsold inventory. When air shipping first began to displace ocean freight in the mid-20th century, it cut weeks off of transportation times, enabling perishable goods to survive much longer trips. That trend has only accelerated as aircraft technology has improved, according to David Hummels, a Purdue University economist.

"If there is uncertainty in demand plus lags between production and final sales," Hummels wrote, "firms may face a mismatch between what consumers want and what the firm has available to sell."

So the less time goods spend in transit during the production and distribution process, the more efficient companies can be at supplying consumers' desires. But what if companies could dispense with shipping altogether by "manufacturing" goods near their final destination?

That's where 3D printing comes in. By producing goods in exactly the ordered configuration precisely when they're needed, 3D printing is ideal for filling gaps in the supply chain (which reduces uncertainty), keeping inventory low more generally (which saves companies money on shelving) and reducing waste (which occurs when the goods aren't sold).

Advocates for 3D printing argue that even on its own, the manufacturing technique could upend the retail sector. A small or non-existent inventory gives a business much more freedom to test new products. Suppose you sold a lineup of coffee cups that were only manufactured as people ordered them, said Hod Lipson, director of Cornell University's Creative Machines Lab. You could post a handful of options on your website at little to no cost to you, then delete the low-performing cups without having to make them all first.

"That would be very costly to do if you actually had to fill up a whole supply chain, a whole production line, for each of those items," said Lipson. "But when you're printing them or fabricating them on demand, you can much more easily evolve and adapt your production to what output people actually want."

The limits of 3D printing

The dream of thousands if not millions of American entrepreneurs doing business this way is enticing. But this is where the promise of 3D printing bumps up against reality. There are concrete limits to just-in-time manufacturing that make universal adoption unlikely.

One major hurdle is that while printing with most materials singly is a cinch, printing with more than one material at once is much harder. A typical room might contain objects with 50 different materials in various combinations. To print an object in said room, not only would you need to have all the necessary materials on hand in a printable form — you'd also have to have a printer with multiple or interchangeable nozzles. As if that weren't difficult enough, each new material might need to be printed under different conditions.

DJ Butenschoen works for an Illinois-based company called GPI Prototype and Manufacturing Services, Inc. The company 3D-prints metal parts by laying down a powder and then tracing a design with a heated laser before applying more powder and repeating the same process, over and over again. (All 3D printing operates on the same idea in one form or another.)

"We have seven different metals we build out of," Butenschoen said. Each one of them prints at a different rate. "Sometimes it's how focused the laser is, is it quick, is it slow — so having the ability to put multiple metals in there, you'd have to have multiple lasers and multiple everything. And then you're putting three or four machines together just to make one part."

As labor-intensive as the production sequence sounds, it's the finishing process that often demands the most attention. After all, even the simplest bobbleheads and figurines generally need to be decorated before being sold. And that can take time and money, too.

GPI accepts orders from practically anyone, ranging from hobbyists to large manufacturing firms that need complex moving parts. But — tellingly — GPI won't 3D-print something if it can be machined using traditional methods.

The kind of business that GPI does, moreover, isn't the kind of activity that ordinary consumers can safely perform in their own homes. Squirting molten plastic from a tube might be fine, but steel or aluminum, with their higher melting points, are a different story altogether.

The coming future of 'just-in-time'

Nobody, in other words, will be replicating whole cell phones and televisions from their living rooms anytime soon. Traditional manufacturing and standalone factories will — duh — remain a key part of the American retail universe for some time. But in the 21st Century, we'll see more factories that incorporate 3D printing into the production process, allowing more flexible manufacturing and shorter turnaround times.

In fact, there's some evidence that's already happening. We think of factories as being large buildings filled with robots and people in hard hats that consumers never visit, but the factory of the coming decade might wind up being a much smaller, community-oriented destination. Another way to put it is that 3D printing is fast adopting the Kinko's model. UPS — yes, the company with "parcel" in its name — recently announced plans to set up 3D printing shops in San Diego that will let startups and small businesses print their own prototypes. Washington D.C.'s public library system has its own 3D printer that anyone can walk in and use. And New York-based Shapeways already accepts your 3D designs and prints them for you.

The last of those represents an early mix of traditional shipping and 3D printing.

"Shapeways is taking the Amazon model," said Chris Dixon, the Andreesen Horowitz investor who sent Shapeways $30 million in venture capital earlier this year. After printing a customer's product from a 3D design file, he said, it then gets UPS to deliver it.

Shipping to U.S. locations currently takes 2-3 weeks. But when UPS opens its new 3D printing centers nationwide, Shapeways could conceivably slice that delay down to the time it takes a customer to visit a printing center, feed a copy-protected version of the design file into the machine, and print the product themselves.

Amazon's giant fulfillment centers could be another place where just-in-time manufacturing and delivery come together. Today, the company might be focused on getting things from its facilities to customers quickly. But that inventory has to be restocked for the next customer from someplace. To the extent that 3D printers can help replenish inventory locally, that could add up to a great deal of savings.

Adding 3D printers to Amazon's business wouldn't just be good for Jeff Bezos. It'd be a boon for 3D printing advocates looking to spread the technology far and wide. Even if home-based 3D printing remains a niche activity, MakerBot CEO Bre Pettis expects that within 18 months, most people will have held a 3D-printed object in their hands.

"The next big threshold is when everyone knows someone who has access to a 3D printer," said Pettis. "You'll be the person friends come to and say, 'Take me to your leader.'"

With these new hybrid ways of getting products to consumers, that point could arrive even sooner than we think.