How it is possible to make Aqua Regia in the lab?
Typically, 1 part of concentrated nitric acid is added to 3 parts of concentrated hydrochloric acid. 


Personal protection (goggles, gloves, lab coat) is vital. 
Prepare and use it under a well-vented fumehood only - hands inside the fumehood, head outside!


UPDATE

The comment of Crystal Lettuce is very important and points to a crucial aspect:

Aqua regia isn't a mixture to keep bottled on the shelf: it has to be prepared and used immediately!