Most people refer to it as a clothes pin; in Hollywood it’s referred to as a C-47. They were named that way because back in the day there were 47 pins in a pack. The C stands for clamp, hence C-47.
We’ll take them and reverse the way they clamp so that they have more of a pinch tip to grab stuff better:
I like using these economical tools for clamping gels to lights and softboxes. Jo-Ann Fabric and Craft stores sells them in different sizes and colors. 
I like using the medium clamps to secure gels inside small to medium softboxes:
The large clamps are great for securing gels onto grids on softboxes:
This is just one of many ways standard household items can come in handy on a photo shoot.
I hope you enjoyed this tip, look out for more. Thanks for giving me your time.
That’s a wrap, fade to black.
For those who know German: Recently I had published an article on more or less unusual items that should be found in a photographer’s gear bag. C-47s are mentioned in the paragraph on A-Clamps. http://www.primephoto.de/zusatz-ausruestung-immobilienfotografie/ (English version is not ready, yet.)
With the cloths pin, I think it could be made just a bit better. Cloths pin exert a lot of pressure and could leave marks or actually do damage. My idea is once the pins have been converted, take a
piece of sandpaper and clamp the pin to it. Then pull the sandpaper out a few times. What this would do is enlarge the clamping area and even out the pressure spot.
Great suggestion
With the cloths pin, I think it could be made just a bit better. Cloths pin exert a lot of pressure and could leave marks or actually do damage. My idea is once the pins have been converted, take a
piece of sandpaper and clamp the pin to it. Then pull the sandpaper out a few times. What this would do is enlarge the clamping area and even out the pressure spot.
Great suggestion
For those who know German: Recently I had published an article on more or less unusual items that should be found in a photographer’s gear bag. C-47s are mentioned in the paragraph on A-Clamps. http://www.primephoto.de/zusatz-ausruestung-immobilienfotografie/ (English version is not ready, yet.)