And here we have our sample, already a brush.

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Now I will make another but similar brush from I have already have. Actually there are millions of ways to modify and rebuilt Brushes in Photoshop. You can create brushes almost out of anything.

For modify my brush I will just use layer styles as a tool.
Switch to our Brush document and apply several effects to our cross. Here is our result if taking it in the future.

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And here are layer styles. Remember that the Fill is set to 0 (zero) %.

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Here. Define this brush as well. Here we have our Hollow Cross Brush.

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Now all that remains is to test the brushes. Make a layer and begin to paint.

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Draw some crosses changing the opacity to form background of the image.

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I did with my tablet but it can be easily be done with mere mouse.

Here are the setting who will make this with that tablet.

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