Basically for Back to Mac all you need is 6 contaniers,empty or full doesnt matter..
the contaniers for example are: eyeshadow, lipstick, lipgloss, foundation, mascara, blush , perfume and ect.
no eyeliner pencil. anything that has a plastic contanier because basically its just to recycle.you can get a lipstick for free. If you go to a mac store, you can do the same thing and pick either an eyeshadow, lipstick or lip gloss. The counters only give lipstick. Also make sure if you already depoted you eyeshodow to put back the silver contanier because some Mac stores dont accept them if there missing the silver contanier.
you can also do this online.http://www.maccosmetics.com/giving_back/btm_return_packaging.tmpl