1. Hold a separate account or use a specific ETF or mutual fund for this to keep the accounting simple
2. No cheating by transferring cash obviously.
3. Transfers from other cash back cards or sign up bonuses are fair game. Churn like you’ve never churned before, but keep it above board.
4. Cash bonuses from investment accounts or banking sign-ups are fair game. The unfair advantage of these bonuses is balanced by the PITA nature of these bonuses to pull off.
5. Use any index ETFs or mutual funds you like.
6. Feel free to cash other CC points, but be mindful the are usually best used for travel rewards.
7. Personal spending only - Sorry, dude with the $2M yearly spending CC thread.... not invited

Post your play by play tricks you are using to build up your holdings.
For some inspiration, I’ve been doing this for 5 months and managed to build up $700 now (I’ll race to $10.7k). I’ve done:
1. Fidelity cash back CC signup bonus - $200
2. DiscoverIT CC first year bonus - $136
3. Misc spending - $364
4. Using US total market mutual fund FZROX as my fund - 0% ER
7% of the way there! I’ll update every couple months.
Good luck!