The ingot is shown with a flat back and rounded edges, as well as a number of cutouts for controls and extraneous holes said to be for mounting to manufacturing machinery. Along the sides are allowances for what appear to be volume rockers, the ring/silent switch, a SIM card tray, and the new side-mounted lock button.
Along the bottom are cutouts for an iPhone 5c-like speaker grill, lightning port, headphone jack, and microphone. Oddly, the microphone on the bottom of the device is the only one shown in the tool -- the microphone found next to the camera on the iPhone 5, 5s, and 5c is not present.
Also making an appearance are a raised ring for the rear-facing camera and the rounded flash, a departure from the dual-LED True Tone setup Apple introduced with the iPhone 5s. As noted by MacRumors, the form is not designed as a mockup of the final product -- it is, rather, a manufacturing tool -- but the departures are suspect nonetheless.
Finally, there is no word on the steel brick's size. Apple is widely expected to increase the size of the display on future iPhones to 4.7 inches, with a 5.5-inch "phablet" version also rumored to debut this year.
Case makers have bet -- and lost -- on rumored iPhone designs before, most notably in 2011 when it was claimed that Apple was working on a completely redesigned iPhone. That year, the iPhone 4S debuted with a design largely identical to its predecessor.
Apple did revamp the look of the iPhone a year later, when the iPhone 5 launched with a new, taller 4-inch display. The company has been on a pattern of redesigning the iPhone every two years with a new model number, while the "off" years are used to introduce "S" models with improved specs and new features.