Hmm... excellent question. How about a device that allowed me to travel in and out of any book, film, TV دکھائیں یا video game at will? Or... a portal that allowed me to travel between worlds? My brain is a bit cheese-like at the moment, so I'll probably come up with some better ideas later and ترمیم them into this answer.
Hooo I like your idea about the elixer :D Foooood<3 anyway ;3 I would invent a ہیلمیٹ to help me get the کتابیں written material into my head, in a short time, so I will not waste time learning for exams :DDD And of course I will be installing a button to خارج non-essential information in order to not overload my brain :}
Or, in a different thinking direction, make up a کرن, رے reduces the calories of food to 0, so the food will be the same thing! only he could not make us fat, then we can eat as much as we want!!! :D That's about what I'm doing now ... But would not hurt to invent something like that ^0^
A way to clone myself but to also morph back togehther with the clones, so we could learn a bunch of information at once bt morph together to remember it xD Oh and something that can make آپ shapeshift... and this thing that would let me imagine a picture and create it without actually drawing it out, that way, my art would look good and I wouldn't have to draw xD
What would I create? That's a toughy, but if i had to create one invention, i'd probably create a lazer that can give us fanguins مزید power so that we can all take over the planet.