I use Microsoft Excel to create drafts for my letters since Excel has easier options to adjust size of the letter box and even the letter itself
Then, I printed out the letters, two letters fit the 8.5x14 size of bond paper and cut one by one.
I got some wrapping papers lying around so I made use of them. I cut the wrapping papers a little bigger than the letters. I used a double-sided tape for the letters to stick to the wrapping paper.
Punched holes at each letter and used blue string.