There is no argument I haven't heard before about why you want to make your own sunscreen, so I'll ask you not to make one. There is absolutely nothing you can say that will make it okay for you to make something that could be quite dangerous to someone. Sunscreen makes my skin break out so badly and my skin is red all summer long because of the irritation, yet I still use it. I have the skill and knowledge to make something that might resemble sunscreen, yet I would not think of doing it, even though it would save my family a ton of money. You have so many products containing so many different types of physical and chemical sunscreens with so many different types of bases - anhydrous, fancy moisturizers, basic lotions - that there is something you will be able to use. You will have to invest some time and money to find a product that your skin likes - I've been searching for years - but you will find something.