Hi! We haven't responded to a poll in a while; sorry!
Anyway, we had an idea for an OC with a kekkei genkai where she can turn parts of her body into stone. We haven't really worked out the kinks yet, so the idea needs a little more development, but you can use the idea, too, if you like it.
Well, depending on whether you plan to have the earth release user use it defensively or offensively, I can imagine on the defense it'd be more for shielding like Dani said, but on the offense I can imagine like, the user kinda still kinda having having earth form around his knuckles very roughly, and juts out jaggedly like a brass knuckle...
Pretty much nintaijustu seems to be more something like incorporating your element in your physical movement...which makes it sound like bending anyway, so I don't really know if you can do so without it not being like bending...at least with earth release but I dunno. The only example we've seen in the anime is the raikage's lightening release nintaijustu, and all it does is surround him and accent his attacks. But....you're probably more creative than me xD Ayumi uses fire release nintaijustu that accents her punching power much similar to as I mentioned with the raikage. Open flame forms around the parts and appendages she's attacking with (aka arms or feet) to give her an edge.
I was on my way to scream "earth bending" but then I read the poll again xDD I'm sorry XD
You can always use doton to create specific body protections in close combat, or like it's been seen in the anime frequently, to create convenient steps or higher/lower levels to help them attack more accurately. In an MMORPG game I play, the earth element is used to shield the user automatically as soon as their stamina is lower, pretty much acting out of instinct. Does that help?