Traps and Metal Items

Lobster Trap

A very important structure that provides a stable food source. It is placed at the edge of the raft near the water to periodically catch lobsters. No bait required despite the description saying so. Maybe it will be implemented at a later date. Lobsters, when cooked, provides a lot of points for hunger and a reasonable amount of water so it is currently the best food source in the game.

Net for Catching

Net for Catching is a structure that is also placed at the edge of the raft. It is meant to catch floating materials but at the time of writing, it only seems to be getting thatch and not the other floating items.

Metal Foundation

The strongest foundation you can build currently. It would be good but since it uses the much rarer materials like metal, it may be a good idea to just stick to wood foundations. you could fill the outer edges of your raft with metal foundations or just double your wooden foundations.

Metal Wall

Presumably the toughest wall. Same arguments apply on why to not use walls. Maybe in the future if they implement bad weather where you do have to take shelter.

Metal Ladder

A tougher ladder for accessing higher floors. Right now, the difference between a wooden ladder and a metal ladder cannot be clearly specified since we still have not had the opportunity for something to attack it.

Metal Barricade

Similar to the wooden barricade but tougher. However, same arguments in that you can't kill the enemies that are attacking it so they will eventually destroy it and then will require to rebuild it using precious materials.

Lightning Rod

A structure that protects from lightning. However at the time of writing, it seems unimplemented so this structure is pointless for now.

Radio Tower

Used to send out an SOS signal. However like the other structures, it seems like the feature is also not implemented. For now, you can craft it but you will be unable to position it.