I am sorry to dampen you, but the answer is no way. The only two methods of changing your eye color is surgery and contact lenses. Surgery lasts for a lifetime and changes your eye color permanently. While contact lenses can change your eye color temporarily, you said you want to change your eye color without them.
The only way to change your eye color temporarily is to wear colored contact lenses.
In order to change your eye color without colored contact lenses. First, change your shirt. This helps immensely for those with green or hazel eyes. Second, change your makeup. I mean, combined the help of mascara, eyeliner and eye showdow will achieve an alteration, particularly when your color assortment is appropriate.
Third, if you really hate your eyes color, you can take iris implant into consideration. You need to consult an ophthalmologist. He can give advices based on your needs and budget. Certainly, consider surgery very seriously, in which you will suffer surgery risks and a long recovery period.
Another way is to choose opague contact lenses, then you can enhance your natural eye color by a green or brown lenses. If your doctor has some trial lenses, you can see what you look like with them.
All right, I think you are very eager to make some changed to your eye color, but generally speaking, that is impossible. Because our eye color is per-decided by our gene type and some anthropological reasons. If you are really keen on that, you should try to wear a pair of colored contact lenses and you will be ok with your eye health. Just try to pick a pair on Amazon.
If you want to change the eye color temporarily, you will have to use the colored contact lenses. Or else, the surgery will help you change the color forever. When you wear the colored contact lenses, you should not wear it for a long time every day and keep the hygiene on using it. If you do the above ones, wearing the color contact lenses will make you look beautiful and safe.