I really like my Mazda 6, but there is nowhere to put coins!! Now there is. It fits perfectly in the armrest. This is for a 2014, it may/may not fit on older/newer models (see UPDATE section below!), I have no idea. Probably better chance to fit in a newer model as the 2014 is the 1st year of the new model. I don't know if they changed the armrest or not after 2014. If you make one for a different model year, please give the result in the comments section (fit or not fit). Thanks!
UPDATE, MAY 17 2016: Also fits Mazda 3 2016, so maybe any Mazda from the new model. Let me know if you try it in a different model and I will add it here.
Thanks to "tjbenator" for the info.
It needs supports for the tabs on the sides. They broke off really easily for me (the supports, not the tabs!).