Robotic arms and grippers

Lynxmotion Robot Arms
1

How can I make my robot lift blocks if I am not allowed to use any readymade mechanical gripper?

2

If you cannot purchase something, then you will need to design and create it yourself.
Perhaps use other grippers and systems as inspiration.

3

What do you mean by other grippers and systems?

4

See how other companies have designed their grippers:
robotshop.com/en/catalogsear … t&dir=desc