The central component of any grow tower is, essentially, a functioning worm farm. As worm farms are a stand alone unit, which many gardeners keep to produce liquid fertiliser, there's no reason why the worm core can't be established before the grow tower is constructed.
To see how to make the cylinder for the worm core, watch the video from yesterday's post. You'll need to stop water and worms escaping through the holes, so give the drilled cylinder a couple of coats of cling film, and jam the bottom into a plant pot, to stop the whole thing emptying out while allowing the valuable liquid to drain.
Remember to remove the cling film before building the worm core into your grow tower.
About the worms:
The standard earthworm won't do the job. You need 'tiger worms'.
Tiger worms are surface dwellers and can be found beneath leaf piles, or near the top of existing compost bins. They are richer in colour than earth worm Jim, and have noticeable bands, hence the name.
Here are the links to all the details you need to prepare and establish the worm core:
How to find and identify tiger worms: https://www.buglife.org.uk/bugs-and-habitats/tiger-worm
How to keep the worms alive: http://www.redwormcomposting.com/raising-earth-worms/
About Judageddon and Jumping Thumb: http://jumpingthumb.co.uk