I agree a rolling cart is the best solution since Ican’t see therest of the space it is hard to say where it could go.

A lot of the beauty gurus on youtube use furniture from Ikea for makeup storage.

You tuck it where the hair dryer on the floor is plugged into the outlet.......and yank it over to use. lol

The only place I could envision a shelf would be right below the mirror, but I don't like the idea. A rolling cart as others suggested is really the better option. A couple of additional thoughts: Start by having your daughter weed through the products and eliminate what she honestly doesn't use or what's expired. It's OK to use something a couple of times and decide you don't like it! Consider purchasing a different table that has more storage. Also consider only having her basics on the table and storing the extras (cart, drawers, bins). For example, I have one make-up bag that has my go-to, everyday colors. All other options that I use more infrequently are in a drawer in the bathroom. Consider how products are used. My dermatologist said lotions are most effective when applied right after washing. Would lotions be better stored in the bathroom, then? (Mine are in a bin with a handle under the sink where I can easily pull them out). Sounds like a great opportunity to rethink the system!

Thank you so much everyone for the great suggestions. Yes I agree with her getting rid of a lot of it but she works for Sephora and gets samples. I look for the rolling cart idea.

Tackle boxes work well for storing make-up, sewing supplies, etc. & are inexpensive. I made up tackle box sewing kits for my daughters when the moved out of the house. (basic thread colors, scissors, measuring tape, pin cushion, etc. ) They come in plastic as well as metal. Most have a removable top section - some larger ones have 'drawers'. They have a handle on top so they can be taken into the bathroom where the lighting might be better than the small vanity in her room. Small clear plastic storage containers with drawers work well too. Hubby bought a couple to hold different sizes of nails & small tools and keeps them in the basement by his tools. They look nice enough to put on top of a dresser.

a short cart might slide under the vanity when not in use, and she could pull it out.

The other hope is to move the jewelry and use that area for makeup. She doesn't really need to have the jewelry by the mirror nearly as much as she needs makeup in an easy-to-reach place.

I've been known to attach things to the sides of furniture, like that dresser to the left. A pair of Command hooks that will hold a set of shelves made from lightweight wood (1/2" thick), or shoe pockets, maybe? Though there is still a risk to the finish, I think; a very small one, but a risk nonetheless.

Another option: lay a piece of plexiglas across the vanity, resting on the two side drawers. That creates a nook under the plexi that could hold a "drawer" (make a box, using matte board or foam board, to fit the space)

And that box that the three-way mirror is resting on? Could that be replaced with a box that has shelves or drawers in it?

And on the left, maybe one of those makeup organizers, that will help her expand vertically.

Go to Overstock.com and search on "makeup organizer"--there are tons of options. (other places sell them too, but I thought their selection was good!)

Under the mirror:

a chest with only drawers; maybe two, stacked, if they're not tall enough.

And then on the left, maybe a much more elaborate one, with compartments on the top, as well as drawers.

Depends on how much space you have to work with, and if you plan on keeping the current vanity or removing it to make space for the new storage area, budget, how much work you want to put into it or if you want a contractor to, if you want the items to be visible or concealed, how tall she is, etc. You could take 1/2" sanded plywood, paint it, and make shelving that's very durable. They used the rolling carts along with a side table. If you have the money you can get really nice vanity towers ranging from a couple hundred to over a thousand depending on brand/model. You can also contact a local woodmaker. We have the luxury of having a marvelous woodmaker near us and he does custom pieces relatively cheap with install.

It's not this complicated ladies..........weed it out and get a cart. :)