My 3D printer consumes three things: my time, electricity, and miles (*) of plastic filament.

To date, I've been going through plastic at about two kilograms per month. At about $60/kg (including shipping) for the manufacturer's plastic, that's about equivalent to a bad Starbuck's habit--an affordable luxury, especially since I don't otherwise have a Starbuck's habit.

There are two problems with buying plastic from the manufacturer, though: first, it costs $60/kg and I'm cheap. Second, it only comes in white.

So I have been on a hunt for alternative sources of 1.75mm ABS filament to feed my 3D habit. Hobbyist 3D printers seem to have settled on 1.75mm ABS and PLA as the "standard," so there are may sources including other 3D printer manufacturers, third party vendors, and guys who bought a palletload of plastic filament and sell it on eBay.

So far I've tried five different sources of filament and I'm still evaluating two others. I've paid prices ranging from $25/kg (for bulk orders) to $60/kg. And I've discovered that all plastic is not created equal.

Size: To get the best and most consistest results in my printer, the actual diameter of the 1.75mm plastic filament needs to be between 1.70mm and 1.80mm. Plastic as small as 1.60mm and as large as 1.80mm can be made to work with some effort, but diameters outside that range will not feed properly.

So far this has been the largest challenge in finding reliable suppliers. I've bought reels of filament which vary between 1.55mm and 1.95mm over a distance of less than two meters. That's simply not going to work. The result is jammed filament, failed prints, wasted plastic, and frustration.

Of the five suppliers, three have delivered plastic which is consistently in-spec: Up (the manufacturer of my printer), Makerbot (which makes a competing hobby printer), and ProtoParadigm. The guys at ProtoParadigm get extra credit for offering bulk 30-lb spools at a substantial discount, but you have to special-order it and wait a couple months for delivery.

Plastic: It turns out that there are lots of different kinds of ABS plastic. The stuff Up sells is an extra-strong grade which gets extruded at 260C. Most other suppliers offer a lower grade of plastic which they recommend extruding at between 200C and 225C.

So far, every ABS plastic I've tried has extruded just fine in my printer, though with the lower grades of plastic it is often harder to remove support material and there tends to be more warping and lifting from the print surface. If I was trying to get perfect models every time this would bother me, but I consider this a worthwhile tradeoff for having a choice of colors and lower cost.

Colors: If Up offered a choice of colors I probably never would have started looking for other sources of plastic. Right now I have reels of about ten different colors, including glow-in-the-dark and metallic silver (which is more like graphite, but still looks sharp). Printing in color gives much more appealing results than boring old white.

Quantity: Most retail sources sell ABS filament in 1 lb or 1 kg reels, at prices around $45 - $55/kg including shipping. Special colors, like fluorescent, glow, and metallic, often cost a few bucks more. A few carry 5lb reels at a discount. ProtoParadigm lets you special order 30lb reels for a significant discount.

I'm just starting to explore ordering directly from wholesalers. Minimum orders range from 10lb to 25kg, making this a little risky since I don't want to buy a year's supply of plastic and discover it consistently jams my printer. On the other hand, wholesale prices seem to be generally around $20 - $25/kg including shipping, so there's the opportunity to save a lot of money if I can find a reliable source. Wholesale orders also seem to have one to three month lead times.

Stock: Right after Christmas, most sellers of 3D printer filament seemed to go out of stock on most colors. I'm not sure if this is a post-Christmas spike in demand or what, but at the moment it is a challenge to find many colors. I'm hoping that availability will improve over the next month or two as the wholesalers catch up.

My Buyer's Guide for Plastic to Feed an Up

Up: You can't go wrong with the manufacturer's own plastic. Pros: best performance and strength. Cons: comes in white only; more expensive than other retail sources; ships from China so options are limited for quick delivery.

ProtoParadigm: These guys are obsessive about quality, and their plastic works really well. Pros: Competitive prices, bulk pricing for 30-lb reels (by special order), very responsive and easy to deal with. Cons: Limited colors, but they say more are coming soon. Right now they have Natural, Black, Glow, and Fluorescent Green, all in stock.

Makerbot: A little more expensive, but consistently good quality. Pros: Lots of color choices, quick shipping, and easy to deal with. Cons: Right now most colors are sold out; prices are at the high end.

3dPrinterStuff: I can't recommend because the plastic they sold me was consistently inconsistent in the filament diameter. When I complained about the poor quality control they were not responsive. They used to have a good selection of colors and some 5-lb reels, but all they list now is black and white.

3dInk: Also can't recommend because of out-of-spec filament diameters, but the owner was helpful and offered a refund when I complained (I refused the refund and am using the plastic). There's hope here. Very competitive prices and respectable selection of colors, though all but one are sold out right now.

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(*) My rough estimate is that so far I have used about one mile of filament in my printer. Give or take about a half-mile.

There were several new 3D printers introduced at the Consumer Electronics Show a couple weeks ago. The Replicator, from Makerbot, is probably the most impressive from a price/performance perspective: a large print area, two extruders, and fully assembled for under $2,000. Unfortunately, from everything I've seen, the software is pretty much the same as Makerbot has always used, and that's a significant weakness. I want to just print and not have to fiddle with the settings to get good results. Better software and less fussing is why I chose the Up even though it is more expensive.

Another new model, the Cubify, is aimed squarely at the consumer market with a $1,300 entry point and an aggressively friendly look. They take the inkjet printer approach by sellng the printer cheaply but using a proprietary cartridge design to force you to buy the consumables at outrageous prices. It's hard to tell exactly how much Cubify's plastic costs, but my back-of-the-envelope calculation is that it's between $0.10 and $0.20 per gram--which would make it as much as five times the price of the same stuff from a third party.

Despite these new products I'm skeptical that 3D printing is really ready for the mass consumer market. I (and many other hobbyists) really enjoy designing and printing stuff, and I'm willing to devote a lot of time to tweaking my models, seeing what works, and accepting a fair amount of failure along the way. Not every model will print well, and there's a certain amount of art and experimentation which goes into designing a model which gives good results. An ordinary consumer isn't going to expect that.

There are also safety issues. Not loss-of-life-and-limb safety, but lots of opportunities for minor cuts and burns. Parts of the printer get hot enough to burn, and cutting support material off a model entails all the normal hazards of working with sharp knives. I speak from experience, since I was careless when trimming the support raft off one of my models a couple weeks ago. The knife slipped, and I needed seven stitches in my finger. I am now much more careful, but these kinds of injuries will be common until multi-headed printers and dissolving support become the norm.

I still think there's a good chance that someday 3D printing will be a mainstream household technology. Just not today. For all the breathless press coverage over the past few weeks, this is not yet ready for the average Joe and Jane.

I got my 3D printer late last week and have been having fun making a variety of models to see how it performs. I bought the Up Plus instead of one of the many kits like the Makerbot or the Reprap. The Up is more expensive, but everything I read suggested that the kit-based models require a lot more fussing to get working properly (even if you buy them preassembed) and the software is fairly painful to work with.

The Up, on the other hand, comes fully assembed and tested and has relatively user-friendly software which works out of the box. The software is a big deal, because it will automatically add support structure (for printing overhangs) and take care of other routine chores without too much tinkering from the end user.

Most hobbyist/home 3D printers work through extruding a thin filament of melted plastic--imagine a hot glue gun mated to an old-fashioned pen plotter. There are probably a dozen different basic technologies for 3D printing, but this one seems best suited for the hobby market: it is relatively inexpensive, the materials are also cheap and readily available, and safety issues are minimal.

On the downside, this method is slow, and limited in the materials you can use. The core of the unit (and most expensive component) is the print head, so hobby printers generally have a single head. That means that each model must be made from a single material, so only one color of material can be used and the support material has to be the same stuff as the model itself.

Professional units often have two or four print heads--that lets you use some other type of material for the support (making it easier to remove all the support scaffolding), and have several colors of plastic included in the same model.

I've posted some pictures of models I've build on Thingiverse. So far I've found that the printer can produce really amazing output, though sometimes the software needs some tweaking to get the best results. Support material is a pain to remove, so it's best to use the least amount of support which will still give good results.

I've also found that kids (of all ages) find the 3D printer endlessly fascinating--it's a great way to inspire interest in designing and building stuff, and my kids have already started making models in Sketchup to print.

A personal computer in 1975 cost about $2,500 in today's dollars if you bought it assembled. It didn't do much, as there was no third-party software and it only had 256 bytes of memory. (However, for an extra $1,350 in today's dollars you could upgrade it with another 1,024 bytes of memory). A few thousand units sold that year, which was a shocking success.

As a laughably downsized version of what were then giant industrial machines, it was hard to see then what a personal computer would eventually be useful for. It would be another four years before Visicalc--arguably the first really useful thing you could do on a personal computer.

So would you have bought a personal computer in 1975?

In retrospect, many people would probably say Yes, but that's only because we now know how the technology evolved. It's much harder to be in 1975 and see how this expensive toy (which is all an Altair 8800 would ever be) would change the world.

It's this line of thinking which made me decide to buy a home 3D printer. I want to learn about this new technology not because it's useful today, but because it has such interesting potential over then next 10-20 years.

Commerical grade 3D printers are powerful pieces of industrial equipment, and have no place or purpose in the home. Their smaller cousins have only been on the market a couple years and are pretty much expensive toys with limited practical value.

On the other hand, a small 3D printer isn't much more mechanically complicated than an inkjet printer (in some ways it is actually simpler). There's no reason that, with enough manufacturing volume, someone couldn't sell a 3D printer for only a few hundred dollars and put one in every home.

The only reason nobody's selling millions of cheap 3D printers is because nobody knows what your average household would do with one.

I don't know if we will discover the Visicalc of 3D printers, the killer app which transforms this from expensive toy into useful tool. I don't think a lot of people in 1975 knew what the future held, either.

There was another interesting piece of industrial technology scaled down for home use which came around only a few years after the Altair 8800. Unlike the personal computer, however, not too many people today have a personal robot.