Max farm affix is 650% gold find, 650% luck and 200% (+100%) item drops. Half of 650% is 325% and half of 200% is 100%. Those halves are what you need on two characters.
To get there, you must have half of each on each character and providing you have difficulty bonus to make things much easier.
Easy starter is 350% difficulty bonus luck and gold from m3. Then having fortune on both characters makes it 400% overall. You also get overall 50% item drops.
Now add 1 crystal affix luck on both characters and 1 crystal affix gold find on both characters. This should turn the 400% into 625% gold find and luck. Furthermore, add at least 1 greed nature and 1 luck nature on two characters and voila: 650% gold find and luck (+fortunate).
For item drops, since you already got 50% from fortune overall, add 3 item drops ruby affixes on two characters and it ahould go to 200% (+100%).
If you do get epiphany (5), the new caps will be 812% gold find, 812% luck and 250% (+100%) item drops. You must have half of these on both characters. Half of 250% is 125% and half of 812% is 406%.
350% M3 bonus of gold find and luck.
Having fortune at 20 on both characters gives overall 50% of gf, luck and ID. Gold and luck becomes 400% whilst item drops is 50%.
Now add at least 2 crystal affix of luck and gold find on both characters since your using epiphany (5). This equates to 450% extra gold find and luck on average. 400+450= 850%. Boom! Capped at 812% in a way (+fortunate).
For item drops this time, just add 4 item drops affixes on two characters. This equates to 200% item drops. With fortune 20, 50+ 200= 250% item drops. That is capped item drops (+100% hirling item drop bonus).
However for the epiphany method to work, I find that I need to have epiphany on two characters. Obviously, you can also use epic affixes but that can be more costly affix slot wise.
There is a bug though where gold find doesn’t seem to apply to the averaging rules so you don’t have to add gold find on two characters atm. Luck and item drops are following the equation fine.
Capping to maxed though is very hard on very easy mode because it takes so much slots that dmg is less room but it is very easy mode we are talking about. It just takes more effort that’s all. You’re generally better off maxing farm affixes in m3 mode.
This is the guide I followed and it isn’t out of date so it’s still useful. The advice I gave you is as simple as I can get it. No simpler really.