Hi Hackernews, we wrote a post to guide you how to DIY code your own ETF. This should show you how ETF works and how you could even come up with something better. We also attached the complete notebook in GitHub for you to start your research easily in python to science the ETF world. We appreciate any comments and feedback how we could use algos to do passive investment ourselves!!
https://blog.alpaca.markets/blog/2018/8/23/python-notebook-research-to-replicate-etf-using-freedata