Backstory: Recently I was searching for some custom branded content something like a koozie or nicely bound notebook. Redbubble and others have decent generic items but when trying to find something specific it becomes hard and direct to China becomes an option.
The Idea: A niche branded item service.
Deep Dive: Similar to how sticker mule adopted premium stickers, you would find a niche such as alcohol products or notebooks and find a bunch of premium products to offer your customers. You would build or leverage an ecommerce platform such as shopify to sell your items.
As you find your first few customers, you would ask them "what else?" they want to expand your line appropriately.
Validation: Sticker mule is a great example of this "niching down". You can mvp this by breaking even on the first few just to find a market with sufficient demand.
Monetization: This is another ecommerce physical play, watch your margins!