The best money in Elite:Dangerous (2 billion credits / hr): Spire Orthrus Farming

Example gameplay of what is currently, and maybe has ever been, the most effective way at making credits in Elite:Dangerous.

Orthrus Farming Builds Info

For a "high investment" build, go with the reliable TitanKiller explained here (maybe just replace the largest HRP for a class 6 SRV bay); that will double as a Maelstrom build should you choose to go Maelstrom diving in the future -    • The "Titan Killer" Krait Mk2  

Alternatively, you can kit it with missiles for a bit more DPS (Sirius pre-engineered ones being the best, but also the most "expensive" in terms of materials required), but the difference, especially in a group, isn't huge, and kit it with a vehicle hangar for SRV ops (ideally filled with Scorpions, not the default Scarabs); this is probably the most mix/maxed build for this purpose: https://edsy.org/s/vpfit2h

Or, if you want a "low investment / no-grind" version, something like this can be bought with credits only, requires no engineering, and works very well: https://edsy.org/s/vDV0fzV