Shopmade Bar Clamps made of hard woods based on my drawing. I cut small pieces of threaded rod and placed them inside the slide of the clamp. The swivel part of the threaded rod was fashioned by filing-off the thread near the end and sp.
All you need is a small amount of vertical space around a balcony or an open window which can hang or store a vertical array of drink bottles that can grow all your herbs and lettuce easily. Recycle as many of your plastic drink containers.