I don't remember seeing a tutorial either, but I have seen it done. In Photoshop, you can use the eraser tool and set the brush spacing setting to 150, then holding the shift key (that will keep the line straight) click in one corner and then at the other corner of that side. Just continue around each side. You can start/stop your line wherever you like it and make the brush size as big or small as you like. Hope that makes sense.
I tell ya, no matter how much I know about Photoshop....there is always something new to learn! I did not know about the straight line....hold the shift key Just practiced this and it worked!
I followed the youtube tutorial that @Ga_L Posted here, and managed to make some postage stamps. For this layout, I turned a journal card into a stamp.
