There are rests made specifically for rifle target shooters, and for in-the-field hunters that might be adaptable for some jewelry applications. I know some may be uncomfortable with the gun aspect but consider these just as tools that are intended for steadying, and you may find something that works for you.
Some are just bags, which can be heavy, filled with sand. Others intended to be carried in the field for hunting can have a very light fill.
Some devices can be raised on screw posts or gears and locked in place rather than yield the way a filled bag might.
Here is just one variation of the bag type:
Amazon.com : Outdoor Shooting Rest Bags - Twod Target Sports Shooting Bench Rest Front & Rear Support SandBag Stand Holders for Gun Rifle Shooting Hunting Photography - Unfilled-Army Green : Sports & Outdoors
The following is of the solid, screw-adjustable type:
Amazon.com : Caldwell The Rock Deluxe Front Rest Combo Adjustable Ambidextrous Rifle Shooting Rest with Front and Rear Rest for Shooting : Sports & Outdoors
There are many variations / models available. The tripod / screw rests seem to be quite large, and I’d love to find a small one to rest my arm on while I place solder chips. I’d also love to find an affordable, rock-solid turntable for soldering that doesn’t jiggle the solder out of position.
As you may guess at this point I have a lot of trouble placing bits of solder if the workpiece is enough above my soldering bench surface, say on a tripod stand, and even more so if it is on a shaky turntable.
Just other options to look into…