Noting that some proposed alternatives such as the BFG ships, don't look very "monolith llike", I wondered if Dystopian Wars range might have something a bit more "chunky".
I wondered if these Myskin bombers stood up on end might be suitable alternatives?
The rounded end is also detachable so a square base could be attached if desired, though I quite like the round bit.
Perhaps with these as the obelisks...
Though I've always liked the idea of the Dark Realm Viras as a obelisk proxy, as it actually looks like something speedy rather than blocky, and still necron like.
What do people think? Other ideas?
