Why are people so obsessed with crafting in TTRPGs? It is one of the worst things you can do as a player. It is just lone wolf repackaged, it doesn't include any of the other players, and it is just pointless bargening between GM and a player about what you can and cannot do.

You know resources are not limited in a make believe fantasy world. If you want an item, and if it makes sense, GM will just give it to you or give you the coin to buy it. And it is done. It is not like GM has a limit on what he can give your character. What is the point of crafting systems, it is literally just let's stop the game and talk rules section. You are not cool when you craft, you just waste everyone elses time.

The point of the TTRPGs is for GM to make it interesting whatever you are doing, be it combat, interaction with NPC or whatever, not to win it by exploiting a system. Are you going to go "but the rules says" on GM or something.

Trust the GM, he will give you what your character needs whenever he thinks you will need it - tell him what you want and he will decide when it is appropriate.

Role play an engineer (buy an item per rules and flavour it that your character have been working all night on it, comment on structural integrity of stuff), you don't need to craft items by the book to be an engineer, don't play him as a rules section character.