so i have a question, how do you go about making magic items? how do you scale them for your campaign?
Good question! I think every DM's method is a bit different, so I'll speak on my own.
Typically I go with three things.
Is it narratively good for my game?
is it something that I personally want to make?
is it funny?
This had lead to me to making very personally tailored magic items for my players, such as a hammer passed down through a cleric's family from father to son
to a magical bannana from the shadowfell that tastes different to every one who eats it
Typically to make it 'balanced', if it does damage, you can test out a few dice rolls to see what the average of the dice roll is, and if that is an acceptable number for the party level you have. the higher the party level, the more damage the item should probably do, which means the more important the item is!
where as some things don't always have to have crazy effects. some of them can give advantages, or boost a particular stat. and those same items could have strange effects on them because of that!
like a necktie that gives you advantage on charisma checks, but permanently changes the wearers tongue silvery!
the best thing you can do is make the items and know that if it need to be tweaked, it can. players and DMs working together to make sure an item is balanced for the campaign is the strongest foundation for a good D&D group.
there have been PLETNY of times a player has come to me to recommend a tweaking in the item they were given that is at their expense (for example : a pair of claws that were too powerful, so the player suggested a lower set of damage to make it better)
Don't be afraid to fix things as you go! this is a game of imagination and make believe, there is always room for editing and tweaking! don't be afraid of mistakes!!
and best of luck building to you!
-Mod T.