All you need is water (spring or distilled is the best but tap is fine), an natural oil, vegetable glycerin and a small spray bottle 50ml or smaller. As there are no preservatives, only make enough to last you two weeks max. If it smells off, chuck it out and make a new batch.
You can buy vegetable glycerine from health food shops or online. It's good for skin as a humectant. Glycerine draws moisture from the environment and draws it upon where its applied. That's why it's important to use it mixed with water so it's not sucking out moisture from the top layers of the skin.
The oil can be sweet almond, olive, jojoba or grape seed. These are less likely to go rancid when mixed with water. The oil softens the skin and creates a protective barrier from drying out.
Here is my recipe: 6 parts water, 1 part oil and 1 part glycerin. Play around with the proportions to get to the right mix for you. Give it a shake every time you use it. And that's how you make moisturiser out of three ingredients!