How do I unlock Stonestead/Stone Mansion?

[MagicManICT]

You may be missing glass panes after this most recent update. viewtopic.php?f=39&t=69078 I know at least towers need them, and imagine a few others do, too.

[Enjoyment_2]

I doubt they need it, the most vital guess for me would be that OP don't know the metal itself.
Note: you should get the item discovered by current char, i.e getting it directly from smelter (or (re)smelting the bar from nuggets, though you still need to discover any metal bar in order to unlcok those recipes, which in case you know any metal bar would unlock you Stonestead at least)

[Amanda44]

Just to confirm - it's only the towers that need the glass panes when it comes to the house builds, glass was already included in their mats.

[vatas]

You can also learn metal from someone teaching it to you, or from a material account.