Violins are a bit of a strange design. Classically you hold them up by pinching them between your chin and shoulder (restricting head motion), though in more casual contexts people sometimes use their left arm (restricting hand motion). Neither of these are great! Why can’t the violin stay up on its own?
It can! People have made all sorts of straps, ribs, and counterweights for violins. Some examples:
NS Design Balanced Shoulder Rest:
I wanted something similar for my Stroh violin, and played around a bit. After trying a few things I ended up with a truly silly counterweight design:
Probably one of the other designs would have worked better, but this does have the advantage of a long lever. Those are literal rocks taped to the end.
I still probably won’t play my Stroh very much, but I’m now much less likely to hurt myself when I do.
Actually, I think that arm really adds to the silhouette if the instrument! It’s got me thinking: if you softened the corners and/or added some leather padding it would probably be more comfortable, and if you painted the wood to look like tin or brass it would really lean in to the steampunk aesthetic. If you wanted to put more work in for extra credit, you could attach the rocks by hanging a sack on a chain instead of the tape and maybe put some rivet-looking bumps on visible faces. How well will it travel? Do you need to add folding? Or a way to easily take the arm apart? Maybe not much of an issue if you don’t plan on using the instrument much, but it’s fun to think about!