Create own batter recipe
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There's a fixed number of ways you can combine flour and baking powder and sugar and come up with a result we'd all agree was cake.
There's a lot of variations of flavor, sweetness and so on that you can tweak though. So as pointed out by ChicagoTerry you'll be working within established ratios that work for now.
Eventually someone will come up with a new method of baking, or changing flour or leaveners that opens up a new set of possibilities. Flash cooked foams or something maybe.