Disappointed
I'm struggling to be successful with this little wonderful idea. With practice, I have managed to stamp without stamping the borders.
However, when I start to roll the stamper, even following a penciled line, it seems that the stamper takes on a mind of its own and rolls a curved line. Maybe I need to go slower? Maybe, I need to exert more pressure on the stamper? For now, I am disappointed in a wonderful idea.