How do you deal with clients who want mega volume but have thin natural lashes?

Here is how I compromise with these types of clients: Go down to 0.03 diameter extensions (if you aren't already) and do a dark, dense Hybrid or a very light volume set instead. Use shorter lengths! Shorter lengths (like 9mm-11mm) make the lash line look way thicker and darker without adding leverage weight that snaps the natural lash. You can trick their eyes into thinking it’s fuller than it is just by capping and stacking shorter, lightweight fans. If she sits in your chair and throws a fit because she wants 16mm mega spiders on her transparent lashes, you just have to say, 'As a licensed professional, I can't safely perform a service that will cause permanent follicle damage, but I can give you the absolute fullest look your lashes can safely carry.