"Align" is a stapler that is convenient in such cases. Since the screwdriver that sends out the needle and the clincher that receives it can be separated, "saddle stitching" work can be done easily.
The driver and clincher are attached by a strong magnet, so it is easy to carry. Of course, it can also be used as a normal stapler.
"Align" is also useful when you want to put a photo or card on a cork board. In this case, remove the lower clincher and use only the upper driver.
"Align" is sold at "Quirky", which commercializes and sells ideas from the general public. The price is $ 7, but a separate shipping fee of $ 29 to Japan is required.