here are some sewing machine covers that could be adapted to embroidery machines

I have used fleece to make some covers. It really is great for keeping the light and dust out and I have a lot of it. I have also used an old damask tablecloth that I extended with other fabric. Very pretty to toss over my multi-needle machine. All of my covers have embroidery to dress them up. I think tapestry or upholstery fabric are great choices. The nice thing, is that you are the artist/creator. Do what you like with what you have and be proud of your creation.

I made one for my Bernina. Unfortunately, I didn't have enough fabric to include the embroidery arm in the cover. I still use it, but don't have any more fabric that matches my window treatments. I left the side a flap so I could put it over on the side where the arm goes.

Here are the ones I made for my HV machines. You can try to find some coordinating fabric to use with what you have. Doesn't have to be all the same. I used a light/medium weight upholstery fabric that was soft yet still has a bit of stiffness to it. Good luck with your project. Nan W