skin folding

ok so i have no idea what you would call this so please bear with me. im looking to create a short photorealistic animation of a person. but the trouble im having is i dont know how i would get skin to bend and fold. if you cant see what im trying to describe (cause wouldnt you know it i couldnt find any "hand opening and closing " on youtube.) take your hand and look at the area where your thumb joins your hand. now close it and notice the folds in your skin. how can i make that happen without it just deforming the mesh smoothly?

Probably the easiest way would be to use shapekeys driven by the rotation of the thumb (or potentially just manually keyed if the animation is short and fairly simple). If you search around for corrective shapekeys you should find tutorials etc.

If you are feeling particularly masochistic, you could also try modelling some of the bone/tissue structure underneath and use a cloth simulation or something on the skin. I would advise against this, as I suspect this would be very difficult and frustrating to get right.

actually that was another question i had if that was possible cause i was gonna do that to make the bloodveins in the hand under the skin. with a volume (scatter?) for the skin in this and another simulation. unless you know a better way to show the blood veins. open to suggestions on that. general guidance is ok on that as i doubt anyone wants to make a tutorial on that.
ill deffinitly search those shape keys thanks for that pointer as i currently have never heard of them.
just suddenly found myself compleatly fascinated by hands recently (organic and mechanical((due to the one on the feature row )))

My advice is, don’t get too hung up on it. Without a proper muscle/tendon system, and considering Blender’s lackluster shrinkwrap, soft body, and cloth sims, you’re basically fighting a losing battle. Even super high end hollywood movies don’t sim hands and fingers.

ok then any advice on doing the bloodveins under the skin then?