What is the easiest to acquire material that they can't blow through? What materials can't be blown through in general? --- THE ENDER OF TOPICS! GT: Sighteddeath52 "All problems can be solved with a liberal application of lasers and/or explosives."
Any dungeon Brick... Pink,Green,Blue Brick are the three dungeon bricks I think. You cannot make them you need to just take them from the dungeon.
And beyond that the only other thing I know of is the top 3 tier ore. Cobalt,Mith,Adam. You can place the ore itself not the bricks. Place Cobalt ore, mith ore, adam ore. It will not take damage from explosives.
I'm pretty certain, as well, that you wont get any/as many clowns if your house is surrounded by hallow. Instead, you'll get a lot of unicorns, fairies, and gastropods. Not much of a step up, but they won't destroy any blocks at all. --- If you think my name is silly, you should call me either Rob or LaughingThesaurus. No need for being strictly formal on a message board, right?