For many, many years, I had answered all questions about whether or not I knit with "No, I don't, that is too modern for me!" and the same is true for crocheting, which is even more modern. So I'm very, very far from being a heroine of the hook - and it's just that who would have been needed for that next step.
As you have seen on the picture with just the weights on and without the heddles, the threads on the loom tend to lump together. It gets better with the heddles in, but they still run together as they near the weights - something that is made much less obvious by adding a spacer cord to the bottom.
The spacer cord is basically just a chain of chain stitches made around the individual threads of each layer, in order. (Obviously in order.) Making the spacer cord was the job I had most trouble with (see above: Heroine of the Hook, not), and it took me three starts to get it right enough to pass muster.
The first tries were made even harder by using the same thread I had used for the heddles (another cotton thread), which has a tendency to split when handled with a crochet hook. The final chain is made with Gütermann silk, and it does do a nice job at spacing.
You can see the difference this puny little chain makes on the picture:
I had hoped, at the start, I might be able to omit the spacer chain - but this picture shows very, very clearly that it would not have been an option. At all.
So, after a lot of cursing and trying a larger and a smaller crochet hook, and finding that no, sometimes it's not the tool but the tool wielder who just needs to practice more at that, dangit, and finding again that it is ridiculously easy to make mistakes, I had finally finished chaining all two layers of their 109 ends each.
Whew.
And with that... the loom is set up completely, and ready to go forth and demonstrate how a warp-weighted loom does work.