It is a very serious business, we being living historians and all. Every tiny detail of the historian's impression must be tested and authenticated.
Not only does the accessory need to be of the appropriate time period, it must also be worn appropriately.
Not all historic accessories fit the one-size-fits-all requirement.
Often an adjustment needs to be made.
That's where the actual sewing part comes in.
Or knitting if it requires it.
But this part...
I can only assume since there was a computer involved that is was some sort of research and it had nothing to do with the photo booth app because that certainly wouldn't be very serious.