I was searching a technique for making the vignette effect without image editing.

Here's a DIY solution that costs next to nothing and offers lots of flexibility.

1. Cut a hole in a piece of opaque paper. Black construction paper would be a fine choice. The hole should be somewhat smaller than the front of your lens; the smaller the hole, the more vignetting you'll get in your image.

2. Hold the paper over the front of your lens with the hole centered on the lens. You can use a bit of tape to hold it in place.

3. Take a picture. A smaller aperture will make the vignetting more defined with sharp focus in the middle; a large aperture will give you less distinct vignetting with a softer focus over the whole image.

Experiment with different sized holes, and even different shapes. You can also use a piece of cardboard tube to vary the distance from your cutout to the lens, or use the tube alone to simulate the kind of vignetting you'd get from a too-long lens hood. You can also vary the material: the last time I did this, I used a not-so-opaque orange Post-It® Note, and the resulting image had orange corners instead of black ones from the light filtering through the orange paper.