Amazon, at long last, is set to launch a smartphone with a glasses-free 3D “holographic” display. Invites were sent out late yesterday for a special launch event on June 18 in Seattle. Accompanying the invite was a hilariously awkward teaser video (embedded below) with the new device just out of frame, with a bunch of starry-eyed first-time users wobbling and bobbling and gyrating to trigger the screen’s 3D effect.

Here’s the video. If you can think of something else that they might be looking at, just out of frame, do let us know in the comments.

Updated: The top of the phone actually appears to be visible at around the 0:40 mark in the video, when the shot cuts to the lady in blue. The headphone jack is on the top — hooray! We’re not sure if this is the result of an awful video editing job, or an intentional teaser. Hopefully the latter, for the video editing guy’s sake.

Amazon has been rumored to be building its own smartphone since as far back as 2011. In 2012/2013, that rumor diverged into two phones: An inexpensive model, a bit like the Kindle Fire tablet, and an expensive model that would compete with the iPhones and Galaxies of the world. The phone being unveiled on June 18 is almost certainly the expensive model. There could still be a cheap phone in the offing — stack ’em high sell ’em cheap is Amazon’s modus operandi, after all — but we’ll have to wait and see.

The most recent leak, from April this year, pegs the Amazon phone as having four forward-facing cameras that track your face, and then pairs that data with a 3D display to create a glasses-free 3D interface. For more details on how glasses-free 3D works, read our explainer from 2012, when 3D TVs were all the rage at CES. We don’t know the exact approach that Amazon will be using, but it’s probably along the lines of a double-resolution screen with microlenses that project half the image to your left eye, and half to your eight. The data from the head-tracking cameras allows the phone to generate the correct imagery for each eye, creating a very realistic 3D effect. According to BGR, which published the most recent leaked photos, the cameras capture infrared light — presumably using an infrared LED that’s hidden on the front of the phone somewhere.

Given how close you usually hold a smartphone, it will be interesting to see if Amazon’s 3D smartphone can also perform eye tracking. Considering head tracking can be done with just one or two cameras, four seems a bit overkill unless you’re trying to pull off some very high-fidelity display tricks.

The big question, of course, is why Amazon has suddenly decided to bring a 3D smartphone to market. Glasses-free 3D will allow for the watching of 3D movies and TV shows, but beyond that, is there much to be gained? Presumably the phone’s interface will also be 3D — but really, beyond the “oooh, cool!” element, is there really any advantage to having a 3D interface on a smartphone? This isn’t a large desktop display that can be manipulated with Minority Report-like hand gestures — this is a smartphone, with an interface that will probably just jiggle around slightly as you move your head.

In short, we should try our best not to be as awestruck about the 3D interface as the people in the teaser video. Given how long it’s taken Amazon to bring this smartphone to market, you can rest assured that it will have plenty of other cool features. While Amazon has had a lot of success with its Kindle tablets, it will be under no illusions about the relative complexity and difficulty of cracking the smartphone market. Expect the June 18 launch event to be very interesting indeed.