Step 1. Set your ball efficiency (cum efficiency) at 100~200
There are some choices, like 
Nuki Nutbutter while balls were internalized, or using 
Equilibricum with big balls (big balls can be achieved by 
Suma Cream).
Step 2. Initially minimize your ball size. 
ReductPro and 
Uthra+ should work.
Step 3. With 2 or more balls, use 
Uthra+ to reduce your ball efficiency (cum efficiency). After ball efficiency reduction, apply 
Equilibricum.
Alternatively using 
Uthra+ and 
Equilibricum, your ball size will gradually decrease, your ball efficiency (cum efficiency) will increase, and your maxCum will gradually decrease.
Step 4. Sometime after maxCum being smaller than 1 mL, applying an 
Equilibricum will cause your ball efficiency (cum efficiency) jumping into infinity (do not apply 
Equilibricum again). Next, increase your ball size, then you have infinite cum.
Warning: 
Uthra+ is random thing. When trying use the "cum efficiency reduction" effect of 
Uthra+, it may cause side effects unless massive save/load.