Thanks for writing this Mr. Samurai. I just got over the student loan hump but I feel pretty good about it at 27 having a graduate degree and being 100% debt free. Now that I’m on the other side it is good for my brain to absorb some of your knowledge regarding passive income investments. I love gleaning wisdom from older folks who have been there and done that. Mentors rock!
If you are not into craft and love graphical designing and digital downloads, then also Etsy is a great option. I sold digital clipart, patterns and coloring pages on Etsy. I earned much more money than I anticipated. This added $500 per month to my passive income streams. I loved the simplicity of it. This is a great way to earn money on the side while you are traveling or working your day job.
I have only dabbled in drop-shipping before when I had an eCommerce platform 6 years ago or so. I think it is something that you could do on the side, but you would want to do in depth research on the industry you want to get into before setting up shop. It may be a little less passive up front, but over time you could take your hands off the wheel.