i just use an empty 2 oz. plastic cosmetics jar (it used to hold sea kelp bioferment from skin actives), similar to this:
12 Jars Glossy White Sample Sizes Creams 30ml / 1oz - eBay (item 370051431931 end time May-19-08 18:50:12 PDT)
mine is 2 oz though. just make sure the jar is airtight or else the foundation will dry out. the MMU jars probably won't work because they are not airtight.
HTH, Kris