There's been a small WD-40 can (aluminum) out for some time, but it's not quite as small a diameter as what you requested. However, how about a WD-40 pen?

If you can live with a pump... re-cycle a small pump container. This time of year, I carry one in my coat pocket that is filled with denatured alcohol. It easily fits your size criteria, including the cap that covers the pump. Put whatever you need in that. Or, I carry some things in 1 oz Nalgene bottles - Kroil, for one, and USP mineral oil for another. A little scrounging and you can be set...

HTH,

Tom