Buy a 300 piece puzzle new or used (just make sure it's complete). Build the puzzle. Carefully flip it over (2 pieces of cardboard or sheet pans work well). Write a letter (Sharpie is easiest) on the back of the puzzle using most of the space available. Write about whatever you'd like. Toss the box or use it for whatever you'd like. Only mail the puzzle pieces to save on shipping. Bubble mailers work well.

Add the swap name and your swapbot ID somewhere in/on your envelope.

When you get your puzzle pieces build the puzzle, read your letter, and don't forget to rate your partner!

US Only due to shipping cost. Feel free to host an international version