I made chalkboard placemats out of black out fabric and chalkboard paint, and they were perfect for the kids' 1st Day of School signs.
They are super easy to make! I bought the black out fabric (usually used for drapes) at JoAnn Fabric, and I had the chalkboard paint mixed at a local home improvement store. I painted a huge piece of the fabric, let it dry, and then I cut it with a rotary cutter down to the sizes I wanted. Voila! I've washed them in the washing machine on "Delicates" and air dried them so far with no issues, too.
I've used printables in the past, but I like having the date, their names, and their new teachers' names on them. In the afternoon, we could easily change the teachers' names to "I loved __________" to share their favorite part of their first day. The best part is that we can use these again and again, and they take up VERY little space.