How to send item or weapon or materials to other player?

You can, but the game limits the ability to do this and it’s almost overkill. It is done by tapping the location “nearby” icon to the lower left of the chat box. Select the player you want to give something to and select “send gift.” They must first confirm on their own screen to accept something from you. Once they do, you will see to the left of the pop up a list of eligible items you can give. It’s not much at all. What you can give to another player depends on your “intimacy points” you have with them. The more you team and play with them the more points you earn. I reached a level of 5,000 points with my roommate, and then 10,000 points, and they still can’t gift me The more common materials I needed. New items are added at each milestone.

As far as I know, you cannot gift a player weapons, tools, or even food. I understand the limitations between all random players, but it shouldn’t be so restricted to roommates.