The amount of money you’d have to invest just to start a REIT or an ETF would shock you. Just to get the ticker symbol the cheapest way you’d be looking at buying an existing company starting around 50K. Then there are so many regulations and requirements, not to mention ongoing fees... It’s honestly not realistic unless you think you can raise millions and immediately start producing millions in revenue.
A better idea might be to do a token using a coin like Ravencoin and having all your investors completely unprotected with nothing more than a wink and a smile that you’d ever return anything to them. If you have a good enough reputation you might be able to raise some funds, and with an established track record of payouts you may be able to entice new investment. There are too many issues to list that you’d have to overcome even going this route, but it’s possible.
I’ve personally looked at doing something like this with funds I have sitting around for NastyMining, but the only decent solution for me is investing in untaxable assets, which exist under certain US laws, but pay a very low return and would likely not keep up with just holding BTC.
I wouldn't do a full ETF. I'm interested in the new fundraising rules https://www.inc.com/jeremy-quittner/title-three-finally-a-reality-for-small-investors.html