When you go shopping for a car, are you likely to drive off with whatever happens to be on the lot that day, or are you a buyer who likes to customize? Maybe you know the engine you want, the tires you want, and have everything from color to trim to the options package worked-out to a T. The ability to have such control over your purchases is a luxury that's extended to other fields – you can have a computer put together with nearly any combination of specs you can dream up – yet it hasn't made its way to the world of smartphones... yet.

Last week, a rumor suggested that Motorola might offer its X phone models through online sales that would let you customize hardware specs, and have the phone of your design delivered to you in just a week. While you already have your choice of things like color or storage capacity when shopping for many smartphone models, this theory went one step further, suggesting Motorola could even let users choose how much RAM their phones would arrive with. While this is very much an unsubstantiated rumor for the moment, I'm giddy with excitement at even the potential for it being true; the ability to customize a smartphone like you would your car or computer is long overdue.

This idea of buyer-customizable smartphones is one we've tackled before (and even if this Motorola rumor doesn't pan out, it's one we're sure to pick up again), most recently back after the CES when Michael Fisher, rolling with an idea Jaime Rivera put forth, talked about what à la carte smartphone sales could mean for a company like HTC. As I take a look today at what custom hardware could do for smartphone sales, I'm less concerned with who's doing it, or what impact it could have on their bottom line, but about the possibilities (and limitations) presented by this business model.

Your Options

What could we really hope to choose from? There are a lot of components that go into our phones that we might want to have some say over, but the realities of manufacturing are going to ultimately dictate what's possible in a build-your-own-phone environment.

The single-most limiting factor of a custom smartphone is going to be the body. There simply can't be a custom frame for every combination of components under the sun, but we might hope to get at least a handful of different options, hitting some common form factors – maybe a 5.5-inch phablet, a 4.8-inch model, and a 4.3-inch or even 3.7-inch option. I'd expect all of these to be a little larger than a typical smartphone, as they need to accommodate a range of hardware options. That could mean less-than-attractive things like larger bezels than we'd like to see, but this is the price you pay for choice.

We've already talked about memory options, which is a bit of a no-brainer, but what about things like microSD expansion? Here, we hit another stumbling block. We hear about OEMs leaving out microSD support generally for one of two reasons: to make the phone sleeker, or to simplify storage options. This custom phone would do nothing to help things with the former, as I doubt that all those case options would be available both with and without microSD slots; they're really about as supporting as many of the possible options as they can. Instead, choosing to go without microSD might make your phone slightly cheaper, though likely not by much.

Displays give us a little more wiggle room. You could probably fit either a 4.7 or a 4.8-inch screen on the same body, and we're seeing an increasing number of resolution options. While resolution will be somewhat tied to screen size, there's no reason why a 4.3-inch display couldn't be available in WVGA, qHD, and 720p options, all at corresponding price points. Heck, maybe someone has some old 3D screens they're looking to unload, and that could even be a possible configuration.

Not everything is worth having as an option, though. Many of the chips in our phones do double-duty, integrating a number of functions in one package in order to save money. That makes going à la carte tricky, but it's not impossible. Some SoC vendors, for instance, sell their chips with different options enabled depending on what features the OEM wants; while the hardware may be capable of even more, only a subset of them are activated, based on how much the OEM wants to pay. It may not save as much money as simply having those capabilities altogether absent, but being able to selectively disable them at least creates more possibilities.

Speaking of SoCs, I can't imagine manufacturers of custom phones offering more than three or so options. They're going to need basic circuit designs for each of these chips, and it would simply be untenable to support every configuration under the sun. I'd look for a high-end, mid-range, and budget/low-power offerings.

Roadblock Ahead

Radios are probably the single most useful smartphone component to be able to customize; how many times have you lusted after a phone that simply wasn't compatible with your carrier?

But they're also potentially the most problematic, all cause of a little thing called the FCC. It will go by other names in other countries, but most nations have their own regulatory authority that smartphones need to be cleared by. They want to make sure that no one's sending off any spurious emissions, and when we're talking about a skeleton of a smartphone with hundreds, if not thousands of different configurations, that's a lot that could go wrong.

I don't pretend to have an easy answer here, but it could come as separately-certified communication modules, bundling together all the antennas, RF hardware, and modem components into one card. Then it would just be a matter of the manufacturer popping-on the one you need when assembling your custom phone. Again, this places limits on phone design, and larger, thicker hardware seems unavoidable, but haven't you always wanted a phone that could work on any network, anywhere around the globe?

Software

Even if all these hardware options came to be available, that leaves the question of software. Custom UIs get a lot harder to do well when you're trying to support a wide range of resolutions, memory capacities, and processor speeds. As a result, we might see custom phones relegated to pretty much stock software. That makes the fact that Motorola's the company tied to these new rumors so interesting; it could easily become the future heart of Google's Nexus series, and we've already seen some upcoming Motorola hardware running very plain-vanilla Android.

Maybe I'm getting ahead of myself. Maybe we really should wait to see how a less ambitious project deals with the challenges of customization before letting customers tweak every spec under the sun. If Motorola offers its customizable X phone with your choice of RAM, is everyone just going to select 2GB anyway? Having all the options in the world matters little if we're all going to pick from the same small subset of them.

I'm really hoping this rumor is true, not just because it's always been my dream to see phones sold like computers, but because I'm very curious to see how consumers react. As Apple has made billions proving, you can do very well by offering users just a few basic choices, and largely deciding everything else on their behalf. Maybe there's no money in selling custom phones; I really don't know, but I'm sure hoping to find out.

Image: iFixit