You can use any image as a tool for sculpting and texturing in Mudbox by applying it as a stencil. You can quickly create custom stencils based on any image copied to your system clipboard, or using the Paint and Sculpt tools. You can save new stencils to reuse later, add them permanently to your Stencil tray, or use them temporarily to sculpt the detail you want, then discard them.
To create a stencil
A semi-transparent stencil editing window displays, indicating you are in stencil editing mode.
In stencil editing mode, you can paint and sculpt to create the stencil you want. See Edit a stencil for more information on editing.
Note that this does not save the stencil, so if you select another stencil, the current stencil is lost. You can, however, select Edit > Stencil again (or press R) to continue editing the stencil.
This opens the Save Stencil As window, letting you save the stencil to disk and specify whether you want it added to your Stencil tray.