Purchase a plastic-covered metal plant stake from your local garden center. They are available in various lengths and thicknesses. Then pick up some sturdy plastic/fiberglass plant pots that have central drainage holes just slightly bigger than the thickness of the plant stake.
In the picture I've submitted, the stake diameter is 3/4" and the drainage hole is 7/8". Only 1/8" clearance, but more than enough to misalign the pots. If you need to amend the drainage hole size, simply drill to suit.
To begin assembly, anchor the stake into the ground or into a large pot filled with stone chippings or anything else that will prevent movement. Slide the first pot down the stake and tip it at an angle. Then slide the second pot down the stake and tip it at the opposite angle. Continue with this pattern until you've reached your desired height. As my tower was over 7ft tall, I also secured it at the top of the stake to the roof overhang with a simple pipe clamp.
Now fill the pots 3/4 full with planting compost and plant your herbs, lettuce, strawberries, or decorative trailing plants. Mulch with pea gravel or small stones so that the compost doesn't wash out during watering. Then sit back and enjoy the fruits of your labor.
It's highly functional and inexpensive, it takes up a minimum of room, and it looks good.