All you need is a flashlight

For this technique you have to experiment a bit to get the light levels that you want.

You simply follow all the instructions for taking Milky Way photos (I have them here) And during your 15 second exposure you briefly shine a light on the subject in the foreground. And I mean briefly! And experiment a lot - taking lots of pictures with different life levels.

This next picture of the Grand Canyon National Park sign with the Milky Way in the background uses the light painting technique.

These next two photos give you a bit of an idea on how different levels of painted light can affect the image and the composition of it. These two pictures, other than the variance in painted red light, are exactly identical. They were taken from a tripod one after the other. But they do look very different.

These pictures also show that you can experiment with different colored flashlights.

This tent was an interesting subject for light painting.

The tree line is a distance away from the camera so I used a strong flashlight to get some illumination on them.