Basically the concept is that you have the enchantment table which can also enchant blocks
the enchantment would "reinforce" those blocks by 1,2 and 3 dmg resistance per level and it only enchants 1 block at a time, not stacks.
lvl 1: +1
lvl 3: +3
lvl 4: +1
upto 6-7 levels
now I almost never use the enchant table, so I can't give my opinion on how much xp would be needed for this to be balanced, so pls post. though I would think it should get rediculously expensive by the 4-5 th lvl This would also only work for: stone, cobble, Iron doors, glass, most fences (not wood) and propably obsidian (for the 1st 3 lvls to not be op), brick, quarts, and a few others, not wood.
there would be a black grid forming on the surface of the block becoming more opaque the higher you go in the enchant; this could also work as a decorative block .
the glass would propably allow 1 less light level to pass through per enchant lvl
why? well if you wanted to make a room that's tnt proof that isn't black or any depressing colour with lights in it (through the glass)? or a castle keep to prevent greefing, or a greef-proof house that isn't made of obsidian? or a bank that, again isn't made of obsidian? you could have a tnt test room looking outside...
pls post your Ideas, and I didn't use the search bar, so if has been suggested before, sorry, then consider this a reminder...
EDIT: an alternate method would be craft this with Iron in the mix