I know there are some complaints about his creations and yes they are a bit outlandish to have been refined this much in the 2 months since they defeated the hydra. However, his mom was a mangaka and his dad was a video game designer so he probably had already spent a lot of time seeing the creative practices which couple well with his transmigration bestowed manufacturing powers and the origin magic from beating the labyrinth.
The thing I don't like at this point in the story is how much of an asshole he has become to strangers. They had nothing to do with his summoning to this world or subsequent betrayal by a classmates. What does electrocuting the rabbit girl accomplish? She was just asking him to listen to her and it could have given him an opportunity to gather intel he needs. It doesn't make him the edgy, cool MC the author thinks it does.