Speculation surrounding an Amazon Kindle smartphone has been rife for the past few years, but it looks like the device is finally coming to fruition. These images show off a prototype of the upcoming handset, which is claimed to be one of at least two that are currently in development.

The images were obtained by Boy Genius Report, which has an impressive track record when it comes to leaking unreleased Amazon hardware. In addition to several Kindle Fire tablets, they’ve leaked Kindle e-readers, and the recently-released Amazon Fire TV.

We have no reason to believe this device is not genuine, then — but given that it’s only a prototype, it’s worth remembering that the final device could be significantly different. We should also point out that this prototype is quite clearly in a bulky case meant to disguise its design, and it’s certainly working.

But BGR’s source has provided us with some juicy details about its internal specifications. In addition to a 4.7-inch 720p display, this particular Kindle phone will have a Qualcomm Snapdragon processor, 2GB of RAM, and a 13-megapixel camera. It will be powered by a heavily-modified version of Android — just like Amazon’s tablets.

The most interesting thing about this device is the number of front-facing cameras it has. There are four altogether — you can see them in the pictures above and below if you look closely — and no, they’re not all for taking selfies.

As recent rumors have claimed, these sensors will work together to facilitate the smartphone’s 3D software effects.

The cameras will track the user’s face and eyes and adjust on-screen elements accordingly to provide a glasses-free 3D effect. Think of the parallax effect Apple introduced to the iPhone and iPad in iOS 7, only much more intense and presumably more accurate.

“The result is a 3D experience without the need for 3D glasses or a parallax barrier in front the LCD panel like the solutions used by the Nintendo 3DS portable video game console and HTC’s EVO 3D smartphone from 2011,” BGR reports.

This will be one of the Kindle phone’s biggest selling points, BGR’s source claims. Amazon will pre-install special wallpapers that move as the user tilts their device from side to side, while some of the handset’s built-in apps — including Maps — will take advantage of its 3D effects.

Amazon is also looking to recruit major third-party developers to develop other 3D apps and games that will be ready for the handset’s launch, the report claims.

While 3D smartphones have previously been a major flop, glasses-free 3D gaming on the 3DS has been a huge success for Nintendo — and right now it’s the only handheld device that offers this. Amazon could muscle in on some of that success if it executes 3D in the right way.

The difficulty will be selling this device to those who have no interest in 3D. Many don’t like parallax effects in iOS 7, and yet they’re subtle when compared to real glasses-free 3D effects. Presumably Amazon will give us the option to disable 3D, but if it’s the handset’s only unique selling point, those who aren’t interested in it probably won’t be interested in the Kindle phone at all.

It’s unclear when the Kindle phone’s launch will take place at this point, and we don’t know for sure that Amazon’s phone will indeed use the Kindle name. But it’s thought we could finally see an announcement from the retail giant this summer. Like Amazon’s first Kindle Fire tablets, it’s also expected to be exclusive to the U.S. initially.

• SourceBoy Genius Report