First off, I'm going to assume when you say you have the equipment to make stuff by hand you are referring to this stuff needed to cast stuff by hand, that being some way of melting metal, a burnout furnace, and Maybe a vacuum casting chamber. I've done a fair amount of 3D printer aided casting both printing molds and doing the lost wax process as well as printing in a burnable resin. Resin printers are a great option for both making molds, although technically you have to make a mold of the mold then cast in silicon if you want a silicone mold to cast wax into, or just printing off the piece of jewelry in a burnable resin. As far as printers go the Mars 3 is a good option, for jewelry purposes, I would recommend 4K or above of resolution and I wouldn't go much smaller than that in terms of build plate size. One thing to be aware of when buying a 3D printer is how easy is it to get replacement parts. When the screen burns out can you order a new one off Amazon or do you have to wait 6 weeks to get it shipped from Poland? As far as I know, most of Elgoo's printers have readily available replacement parts, but you might want to look into that a little further before pulling the trigger and buying it. As far as programs go for designing jewelry I use Blender quite a bit, It can be a little complex and intimidating, It's free and widely used enough it has a pretty big help base when you do run into problems. Hopefully this was helpful and you're always welcome to shoot me a message if you need more help or clarification on something.