Thank you for the opportunity to help you with your question!

The human hand is like an irregular object. To measure its volume, one need to be creative in applying the displacement method. For example, you can fill a large gallon or an two hundred liters tank with water, and deep your hand inside. The volume of water that overflows is the volume of your hand. You can also mark the level of water before and after you deep your hand. Then find the volume represented by rise in height. That height by which the water level rise is the volume of your hand.

I hope you find this helpful. Thank you.

Please let me know if you need any clarification. I'm always happy to answer your questions.