USB cord grommet for a MadCatz SE case

On the stock USB cord in a MadCatz SE stick there is a strain relief type grommet built into the cord thats fits into a square shaped hole in the casing. Does anyone know where I could find a cord strain relief/grommet that would fit a replacement USB cord and fit into that square hole?

No, honestly you are not going to find that, the cord strain relief or grommet as you call it are custom made for the manufacturer.
Most people to for strain relief is make a knot in the cord there they want the strain release before the cord leaves the case.
Zip ties, and cable claps are also solutions. I sometimes source cable claps from replacement DB9 housing.

I really don’t need a direct replacement, but a solution that just covers up the square hole where the new cord is coming out will be good enough for what I’m doing.

Just found this. This is the type of thing I’m looking for, but I have no clue if this is the right size.

I dunno about getting a replacement, but what I have done before on a few devices is to re-use the old grommet. If your new cable is roughly the same size that could be an option. Use a hobby knife to make a single slice down it’s length (or you can stagger it across each segment if you want to get fancy, which will help it to retain its shape). Some are melted/molded to the cable so you actually have to cut them apart, others are just friction-fit.

That sort of fits the bill, but do you know the size and dimensions of your opening of your cord?
The plug you shown is U shape, while you have a square plug. It might work if it measures out right.

You need to get out a ruler and measure the cord opening, or even better than a ruler calipers if you have access to them.

Even then, once you get your grommet on, on the inside I will still see to securing the cable some additional ways, the existing cable snaking, or tiring a knot around a support post or though the knot run a zip line though the knot around a support post.

If he installs one of those linked glands correctly then it will have an iron grip on the cable. No need for anything else.

It’s just a matter of finding the right sized gland. Even a few millimetres difference will make the thing kinda useless without something else supporting the cable on the inside of the stick.

That piece I found is way too big and I can’t find a smaller one. However I came up with a clever solution, an RJ-45 strain relief that I use with crimping RJ-45 plugs with the top snipped away became a perfect fit for the hole.