I used risers for my sewing table, but it still wasn't high enough. It was an old wooden table, so my husband cut four wooden legs and attached to the old legs at the height I requested. I purchased a bar stool so I can sit and design at the table. Very comfy.
The quilters at the Lutheran Church (quilt for charity) use pieces of PVC pipe that they insert when needed. Another great idea. They use on a folding table like the one you have in photo.