Just a random idea

I was thinking that it would be cool if you could have a tool which could be used to increse the durabillity of single blocks making it alot more harder to destroy smaller structures. some Small structures do not seem to last long as they can be taken down by destroying one or two blocks which hold up the structure. Buildings seeem to last longer when they spread across the ground more so if you were able to strenghthen a few certain blocks on the ground layer holding up the building you could build on a much smaller footprint and not have to worry as much about the building suddenly collapsing through a well placed shovel hits by an enemy or griefer.

- hitting a block with the tool should double its strength to pickaxes and bullets
and shovels should not work against them at all

- The tool could work on a system like block collecting so to get more block strength boosts you have to collect more blocks but you spawn with a full 50 block strenghth boosts

- The tool could be a symbolised as a hammer

feel free too tell me the idea sucks...

Like many 'block-strengthening' ideas, it's nice.. but I think only theoretically :/
The game has enough people spamming blocks in awkward places, so making blocks alot tougher/resistant to being cleared may cause more harm than good in the long run.
I like the idea of these types of things, just am not sure how it could be made abuse-proof if you know what I mean.

^Yeah! It would get to the point where we would WANT people griefing.

Like TheGrandmaster pointed out, there seems to be a flaw in every anti griefing suggestion. It's not that the ideas are bad, some of them even seem to work at first. But of course, there will always be a loophole around it.

Great idea, by the way. I just think you should be able to have a small amount of uses on the tool during the whole game. For example, you can have 10 uses on the tool from when you join the game, but you wont regain uses when you respawn.
This helps prevent the spam of stronger blocks.

tGM, feel free to point out the flaw in my suggestion. :)