The postcards were a puzzle that my family members should put together on the 25th of December, the day they would all get together.
I made a stamp from rubber and created a pattern similar to the one of the comfy wool winter jersey and wrote a message that could only be read when the postcards were all together

I sent 18 postcards but, unfortunately, there were two that got lost on the mail.
Even so, I think I worked out perfectly and everyone loved them.