So I'm starting to do castor oil heat packs every night on my stomach. I have purchased 2 bottles of castor oil that come in a roll-on applicator (think liquid deodorant roll on applicator). I need to find a more economical way to buy my castor oil, so I'd like to buy giant bottles of it and re-fill my applicators. I need to have a bottle that can travel with me and can be applied on the spot, so always carrying around a huge jug of it everywhere I go isn't feasible. I need the applicator but would need to save money by figuring out if it's possible to refill these types of bottles. Any suggestions?