What is your budget? I was looking for a similar thing for one of our clients (my company doesn’t do color cosmetics) and it turns out several companies out there sell and label pre-made products. They have a warehouse with unlabeled products ready to go and fairly extensive catalog.
You won’t be adding the colors yourself because that’s not how formulations are made in color cosmetics (ie. you can’t start with a white base and add colors). You will choose colors from an existing range of colors then put them in your labeled packaging.
The company I was leaning towards was charging about $7.00 for an an eyeshadow, for a quantity of 50-500 units. Private message me if you want more information about this company. They also come up on Google searches on the first page so you can start from there.