I am not sure that Photoshop and sketching mix well together. If you do end up sketching in this beast of a tool, please also consider eating soup with a fork and let me know how it tastes. Nevertheless, the awesome team over at Cloud Castle has recently released Basiliq – a handcrafted set of mockup elements for Adobe Photoshop. I think it comes with 300 or so UI elements and icons – maybe even a free cake or something.
Ok joking aside, I think this hip template is more geared at printing bits and pieces for the purposes of paper prototyping. If you do sketch in Photoshop, do let me know how it goes. :)
Credits: Cloud Castle