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I am currently developing a survival game called ‘I am lost,’ and I’m having difficulty implementing the inventory and crafting systems for this game.
Hi, and welcome to the forum! 
Your question how to make inventory and crafting system is very broad, and very difficult to answer in this forum. My suggestion is that you go through couple of tutorials, e.g. when you search Youtube with the phrase GDevelop Inventory Tutorial you’ll get at least five tutorial videos about inventory system.
I’m quite sure you will get ideas and tips for executing the inventory system with those.
This forum is ideal for situations where you try to create something, but you have some specific question how something should be done, or your code is not working as it should be. In these cases, explain the problem as clearly as possible, and share screenshots of your code, so the community is able to understand the problem and help.
Good luck for your game project!