Rigging the hands
Hands are one of the most awkward parts of weight painting in Blender. Very small geometry packed together tightly means painting the correct parts can be a hassle, but the basic concept is just the same as the rest of the body. Take a guess, paint it, stress it, and fix it.
The following diagrams show some ideal starting weights; feel free to use these as a guide:
Figure 5.28 – Finger segment weights
Figure 5.29 – Thumb base weights
Figure 5.30 – The metacarpal bone (used for squeezing motions)
Oftentimes, you may intend to paint one finger but end up hitting other fingers. It’s easy to miss sometimes, but when stressing the fingers, observe each one to see whether any geometry moves unintentionally.
For areas that are hard to reach, you can often use the Blur tool. If surrounding weights are at 1.0 the result of the Blur tool will be close enough...