hi,
Answering your questions:
I want to build a prototype"
The answers to your main question will be found in your answer to this one: Why?
Why are you building a prototype instead of a real gripper? What is it that you don't know? What are you trying to learn from the prototype? Be specific.
Well, it's a real gripper, but it is the first one (new geometry)
What are your restrictions? Finances? Materials? Time? Tools? Weight? ...
Restrictions are mainly soft/flexible materials, with a weight of the samples going up to 5 kg. However, for scale testing, samples with 2kg should be ok.
Budget should be the lowest that allows us to test the gripper experimentally (fully functional gripper).
Servos and their control systems are MUCH more expensive much more complex than simple pneumatic cylinders and valves, but also much more controllable. Does that make a difference to you?
Well yes, because the load we apply (clamping force) varies in function of the thickness of the material and the material itself. This is to be tested in several materials.
Do you want a simple OPEN/CLOSE action, or do you want the gripper fingers to stop moving where you tell them to?
They need to be moving smoothly until they find resistance (material) and compress to a point where the material (sample) is well compressed but is not damaged in anyway.
Do you want to be able to vary the force the fingers exert?
Well yes, as it must be adaptive to the sample's properties and dimensions, namely thickness.
Are the fingers already defined? Is the geometry of their motion already defined? Is it rotary or linear?
Fingers are already defined. Yes, the motion is totally linear (1 translation DOF for the system).
Can you post some images? That will help.
That would not be ideal, as this is a new geometry.
More specific questions get better answers.
Step 1: Define your problem.
What are the (physical) components needed to have a fully functional 2-finger Gripper, whose geometry is printed by 3D.
Thank you for your help and I hope that I was clear enough.