Firstly, you purchase a piece of PVC pipe that the largest piece of the center of your lightstand will fit inside of.
Next, you undo the clamps on your lightstand so that the main shaft and legs move independently, you put the legs up about 8" from the base. Stick the main shaft into the concrete coffee can's pvc pipe insert.
PVC in the coffee/concrete would be a different twist on the orignal post (archived somewhere ).
I can imagine some kid walking through, not looking where he's going and "kicking" the concrete base ... to which he quickly learns to watch where he's going out of concern for his toes (rather than your gear).
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