Here is a little project that the children and you can do.
We measured our felt according to the size of our block crayons. As you can see it was made for our three primary colours. The size of the felt is about 12cm, 4.75in by 14cm, 5.5in.
I then folded over about 4cm, 1.5in of the longer side. I pinned it, then the children stitched along the edge. They sewed according to their sewing ability. Sheth just over stitched. He was 5. Caleb and Hannah did blanket stitch around their edge.
I sewed two dividing lines of straight stitch on my sewing machine, at 4cm / 1.5in intervals. This can be done by hand. This made three compartments for the block crayons.
I then taught Caleb and Hannah how to chain stitch and they stitched the first letter of the colour. You can see it in the photo.