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I believe that the interface is quite safe to use.
The interface is quite safe to use, since most clickable elements are large (predesigned tattoo, tattoo components, the display area). Additionally, The user will be allow to reposition the tattoos, and their respective components. Layers of components should be implemented. This feature will allow users to correct any mistake, making the interface safe to use.
On potential issue is lapses, since there are many gestures to be design to give a good control of the preview procedure, there might be a high chance of lapses if those gestures are not well-designed.