Cardboard lid cut and glued

I made the lid by tracing around the lip of the plastic container on paper to get the outside measurement, then used a ruler to determine the inside measurements. I rounded out the corners freehand, and then exacto'd out the interior. I then used the paper template to mark out the lid pieces on cardboard, and for each container I cut a total of four pieces. Two are solid, two have the inside cut out, and then they were stacked and glued. This way they can sit on top of one another and be a little more stable.