Cedarcreek (OCIN) has a good, lightweight design. I'm looking for a good photo. They use Plastic PVC pipe with a metal spike inserted into one end. On the other end is a T bracket into which short pieces of pipe can be inserted. One side has an SI mounting plate, the other has a conventional punch as backup. A code number can be affixed to the T bracket with vinyl numbers, if you like numbered stands (I know some clubs prefer to number bags, or entire bag/stand combos).
This
photo (showing the stands used for clear and check) and
this one show them in use but don't really show construction details.
I also designed a
base for free-standing (eg urban sprints). These consist of an empty paint can, partly filled with rock or gravel, then concrete mix, with a 8" piece of PVC pipe upright in the center. The spiked end of the stand just inserts into the PVC tube. The handle makes them easy to carry and the size/weight is just right to make them very stable. You can't knock one over by accident. They probably should be painted or something so that they look less like an IED, though...