Trash picking in Jack’s neighborhood is the best. A few weeks ago, I found a beat-up picture frame on the street and snagged it for this project: cheap whiteboard!
After gluing the corners back together, I picked up a piece of acrylic sheeting at the hardware store and cut it to fit. It took forever; none of these Home Depot/Lowes places cut glass, plexi, or anything like it anymore. So I did it myself with a big old blade and a million passes. Paint the back side with white paint, and:
The surface doesn’t seem to love all dry erase markers, but my cheapies from IKEA work just fine (no ghosting!). Total cost: $15.