"Rental properties are wonderful for building wealth ... [but] they're not going to produce a lot of income on the front-end — at least not consistently — because you might make $200 a month on a rental property, but then what happens if a year and a half from now, the heating and the air system goes out on that rental property? That's a $4,000 to $5,000 hit," Carson said. "And so really, the rental property game, as opposed to flipping properties, is all about generating big chunks of cash that you can use to pay your bills, and hopefully, to save money."
If you’ve ever thought to yourself, “I wish there was a product that did this,” then invent it! Create a product, medical or otherwise, and sell it as a company or get royalties for it. It’s not impossible to figure out, I have many friends who have taken a concept to market. Don’t overlook an invention as a fantastic means of attaining passive income.
First: I understand why you would say that such investments are restricted to only accredited investors, because generally, that’s true. There are means, under federal securities regulations and Blue Sky laws in each state, to sell interests to non-accredited investors – but usually those means are so heavily regulated and involve disclosures so similar to cumbersome registration requirements that it is not worth it for the seller to offer to non-accredited investors.
One of the most appealing options, particularly for millennials, would be #12 on your list (create a Blog/Youtube channel). The videos can be about anything that interests you, from your daily makeup routine (with affiliate links to the products you use), recipes (what you eat each day) or as you mention, instructional videos (again with affiliate links to the products you use). Once you gain a large following and viewership, you can earn via Adsense on YouTube.
For those willing to take on the task of managing a property, real estate can be a powerful semi-passive income stream due to the combination of rental and principal value appreciation. But to generate passive income from real estate, you either have to rent out a room in your house, rent out your entire house and rent elsewhere (seems counterproductive), or buy a rental property. It’s important to realize that owning your primary residence means you are neutral the real estate market. Renting means you are short the real estate market, and only after buying two or more properties are you actually long real estate.
When money is lent to a partnership or S-corporation acting as a pass-through entity (essentially a business that is designed to reduce the effects of double taxation) by that entity’s owner, the interest income on that loan to the portfolio income can qualify as passive income. As the IRS language reads: "Certain self-charged interest income or deductions may be treated as passive activity gross income or passive activity deductions if the loan proceeds are used in a passive activity."

One of the easiest ways to get exposure to dividend stocks is to buy ETFs like DVY, VYM, and NOBL or index funds. You can also pay an algorithmic advisor like Wealthfront to automatically invest your money for you at a low fee. In the long run, it is very hard to outperform any index, therefore, the key is to pay the lowest fees possible while being invested in the market. Wealthfront charges $0 in fees for the first $15,000 and only 0.25% for any money over $10,000. Invest your idle money cheaply, instead of letting it lose purchasing power due to inflation. The key is to invest regularly.
Once your audience has grown and you have validation that you’re offering them value, there are many ways to create passive income. You could sell digital products like ebooks or courses, take up affiliate marketing in which you promote other company’s products and earn a commission when you sell that item to your audience, build a community and charge people to be a part of it, create software and sell that, among other avenues. Ask your audience directly what would serve them best, or look at what they’re saying on Twitter, Facebook or other websites, to find out what problems they have and how you could help solve them.
If you love design and you are an artistic person, selling digital products on Etsy could be a great way to earn passive income. Digital products require little maintenance, your customers will simply receive a link to download them (which means you don’t have to worry about shipping and returns handling). All you need to do is spend time upfront to create beautiful artwork! (Easy right?)
The organizing principle behind this grouping, appropriate economic units, is relatively simple: if the activities are located in the same geographic area; if the activities have similarities in the types of business; or if the activities are somehow interdependent, for instance, if they have the same customers, employees or use a single set of books for accounting. 

If you have specialized knowledge in a certain topic, you can put together an online course to teach others. For example, if you have experience in real estate investing, you can create an online course “Real Estate Investing 101”. The benefit of an online course is that once you create the course material, you can sell it to as many people as you want.