I think we should have an upgradeable block that doesn't use iron or wood and its final form is cobblestone, it starts as a stone base, a lot like the wood frame now but it upgrades from bottom to top and uses cobblestones to build the base and upgrade it. Maybe it has a lot less structural integrity than the rebar and wood frames. But I think we should be able to use our stone without having to gather 10000000000 iron ingots.