[@KatherinWinter]
Ya, I basically came up with this idea because there has to be someone out there that can make all these magical items you see all around the world. he of course can't carry a crap ton of stuff on him at once, the types of items he can make is of course changed by how much magic he has, which using the items would also use his own magic supply if they require it. such as magic rings and similar things. He doesn't have any pocket dimension items nor can he create any at his current level. The items are only as strong as his own magic power will allow.

So normally he has to prep items before taking on a job sense he may not have any magic left in order to use an item he creates in middle of a job. The initial item's power is decided by how much magic he puts into it when he creates it, which also determines how much magic it takes to use the item if it requires a supply of magic power. While some items no matter how he makes it like a Magic gun would always have the same magic cost, because the real magic cost comes from the bullets that they use. The type of bullets and how many they have.

So basically have to learn about the magical items that are known in fairy tail's universe and use them as a guide line for what he can accomplish in compare to how much magical power he has at that time and has gained over all, for what he can do.