In this Instructable I'm going to show you how to make your own brush present using Adobe Photoshop CS3. Like many techniques in Adobe products, this can be accompished in near all versions, but the process might differ slightly.
First, we need a picture. I searched google and easily found a cloud picture that will work perfectly for this instructable.
Step 1: Selecting Unwanted Colors
Make a new layer for your cloud picture that you want to create a brush present for. This is crucial because we will be clearing out certain colors and need two layers to do this.
Step 2: Removing Unwanted Colors
Now that the range of blue in the sky we want to remove is selected, pick your Brush Tool and begin removing the unwated colors.
When removing all of the blue sky you will notice some spots needed to be touched up (removed) use your judgement and artistic license here to pic out the spots you don't want to show up on your new brush.
Once we're done with this step, we will set the picture to Difference mode, which will display the exact opposite colors that are being displayed, this will make it easier to remove and finalize the cloud.
Step 3: Finalizing and Saving Your Brush
Now go around and use your brush to remove and finish up your brushset. Remove all of the corners and sides which look choppy and don't flow with the cloud.
When you save your brush, it automatically goes into your current brush selection. When you change your brush present, it will ask you if you want to save changes, click YES or you will lose your new brush.
Step 4: Finished!
Now you have your new brush to use and abuse!
You can do this with just about anything, some brushes take awhile to make depending on how detailed they are and how many colors they have. Also know that the larger you make your brushes initially, the better in the long run. You can decrease the size of the brush from big to small and maintain certain details, but you can't increase from small to big.