1. Open a New Document in Photoshop and paste your image in a separate layer above. Be sure that the image is smaller than the background, so that you have a white border.
2. Choose the Rectangular Marquee Tool and make a square selection on the outside of your image.
3. Goto Select > Inverse to inverse the selection.
4. Click the "Edit in Quick Mask Mode" toggle button.
5. The image will turn a transparent red.
6. Goto Filter > Liquify.
7. Select a large brush size brush and begin pushing the boundries of the box in and out so that it looks like a paint brush mark.
8. Click ok to close "Liquify" and accept the new shaped mask.
9. Click the "Edit in Standard Mode" button.
10. You should now have a paint brush stroke selection.
11. Click the Delete key and you should now have your new paint brush shape border.
8. You can add some extra pizzaz to it by giving it a shadow.
