Some friends and i have played for a few weeks now and have come up with some ideas.
1: Some kind of glass windows. They could be destroyed and be climbed through, but the broken glass would hurt you, and probably have a chance of making you bleed. This would make it harder to enter windows, and easier to defend. (Glass could be made from melting sand.)
2: Barbwire. Made from metal and could be destroyed by a military knife, or some other kind of tool.
3: Digging trenches. Use a shovel to dig. (Would not be deep, but just deep enough to defend from).
What do you guys think? Do this make it too hard to raid, or is this something you would like to see in the future?