Backstory: The founder of liquid death, Mike Cessario, has been making his podcast rounds lately. Every time I hear him talk I'm reminded of how simple of an idea you need to get started, just execute correctly. Not even correctly, just better than the rest. Vitamins and supplements are an old market 

The Idea: Reinventing vitamins.

Deep Dive: I would find a supplement you're passionate about and throw an extreme spin on it, marketing wise. Supplements currently sport those tan, beige and green colors, indicating health and wellness. It doesn't always have to be so tame, you can make it bold, fun, even aggressive. Your ultimate goal is to design a vitamin bottle someone would leave on their desk while sporting your branded t-shirt.

Validation: The trend 10+ years ago was to make everything "healthy and organic," you're seeing a switch to bold and adventurous. Redbull and monster did this with energy drinks, liquid death is doing it with water. Who's going to reproduce it with supplements?

Monetization: From listening to the liquid death podcasts, his margins are pretty slim ~30%. Vitamins and supplements have bigger margins, allowing you more freedom with marketing experiments. Vitamins are something people take regularly, you could take a run at a subscription offering as well.

Steps to Launch: Presell your idea. Mike built a commercial for $1.5k and spent $3k on facebook ads. Within a few months, he had more followers than Aquafina and his youtube video had over 3M views. This initial buzz allowed him to raise a small round to place an initial order.