I havent gotten castor oil yet but have tried olive oil usibg a mascara brush. It seems i get as much on my eyelids as if i had just applied it directly to the eyelidsYou can buy empty mascara bottles & apply like a mascara. I've just been applying with my finger to my eye area and over my lashes & lash line (with eyes closed, of course!)
I've read that coconut oil can thicken lashes... I just made up a batch of castor and coconut combined to see if I can thicken them up some. The castor oil definitely gave me more length.
I also OCM and I do believe that getting my lash line really clean every night before applying the oil helps. I OCM with olive oil and desertroses's comment leads me to believe that this is helpful too.
Thanks for the help!