Kenji,
Stainless steel spice tins (masala dabba) are used in India all the time. You can get some spice tins with little lids for each of the spices. However, for spices you would use on a daily basis, the little lids can be a pain. In my experience, the portions you add are fairly small and if you use them up rapidly, there does not appear to be too much crossover of flavors.
Jyoti
Jyoti
A meal, with bread and wine, shared with friends and family is among the most essential and important of all human rituals.
Ruhlman