Here, Willis is incorporating the unity of shapes (and he'd be a better one to explain it,) but as I understand it, what you're looking at is two shapes joined to create solidity.
There is a central upside-down "U" shape, ending at two legs, and a standard "U" shape running in the opposite direction, kind of reinforcing the first shape, and ending at the points of the elytra on the back of the body.
The antennae are very prominent, but Willis noted they are not particularly "beetle-like." They are insectoid, in a standard way; some beetles do have extended antennae, but if we're being specific to the Ox Beetle, the antennae are not correct.
As a beautiful dame named Sydney rightly pointed out, antennae are important on this character. In point of fact, she said, there is something strangely "sensual, almost erotic" about antennae. Since she's not a freak by any standard, I took this as a thinking woman's addition. There will be a kind of...eerie eroticism about a man-beetle. Considering the intended "love story" of the main character, who must now communicate love as a monster and not a man, it makes sense these probing scent-catchers are inherently sensual in female eyes. Another good instinctual add by Willis.
The lightning bolts on the back are, as Willis said, "kind of like racing stripes." They're additions on the shell, most likely by military men, who adorn the Beetle in much the way they paint slogans on fighter planes and torpedos, as a way to personalize the machines of war. This fits with the notion the Atomic Beetle is, early on, "Government property." Created by a military-funded accident (much like Bruce Banner's Gamma Bomb irradiation,) I imagine the military trying to make chicken salad out of chicken sh*t and failing. Their mistake has cost a man his life, his humanity, his love, his honor, even to a degree his soul. The military will want to use the Beetle if they can, but I think it'll be hard to convince the Beetle he's little more than a cognizant bomb.
In Version 4, upcoming, we will see what is likely the final preliminary design. And it is well worth the wait, folks.
*"Natural elegance" means how a beetle is put together, but not to indicate how it moves and functions. The indicator of "clunky" in relation to the character is part of the charm of beetles...they really are bulky tanks with little agility and the fearless attitude of the insect, which has a very strict life span (four months for the Ox Beetle) and a job to do, usually involving masticating organic material (including dead animals and other unspeakable filth) until it's a ball of mummified wax, and then finding a female to implant some eggs in that underground bad boy so a bunch of beetle larva can roll around in it and chew on it for a while.
Beetles may not be pleasant, but they're incredibly beneficial to the natural environment. Yeh, I didn't know it either. I guess I figured everything dead just ended up as fly and ant food. Wrongo.