Alright, I finally got a response to my email from MAC, and it is totally useless. They don't even mention the metal bits although that is specifically what I emailed about. I have a feeling they just fired off a general response, but here it is anyhow.
Thank you for taking the time to contact us and for your interest in M.A.C.
Because we share your concern about our environment, with the Brand's
inception in 1985 we established the "Back to M.A.C" program: When you have
finished using M.A.C plastic packaged cosmetic items purchased from us,
please bring the containers back to a M.A.C location near you.
Although we cannot reuse these containers for our products, we can make
sure the packaging materials are properly recycled. To credit you for your
good deed, the accumulation of six (6) recyclable plastic containers
entitles you to select one free M.A.C lipstick as our thanks.
Please note: Since 100% of the retail selling price of Viva Glam Lipsticks
is provided to organizations that help people living with HIV/AIDS,
Lipsticks in this series are excluded from this program.
Also, the "Back To M.A.C" program is not available where regulations
prohibit.
We trust the above addresses your concern. We hope that we have the
opportunity to serve you in the near future.
Sincerely,
Tiffany Soriente
Global Consumer Communications