Sharing one of my stone setting tools; cost about a dollar and 15 minutes to make, not including rummaging thru bins in the garage. Making the simple tools is a frugal way to start your tool collection and good shop practice – learn to grind down a screw to make a bezel pusher is part of the skill set needed to make a setting punch or chasing / repousse tools.
This is my bezel pusher, kinda wonky but perfectly usable. It's a brass screw screwed into a graver handle. Brass is relatively safe to use near stones, and the screw head is a good size.
Begin by screwing the brass screw into a graver handle. You could substitute the graver handle for a cabinet door knob, wood ball, dowel, handle made with thermoplastic, whatever is comfortable in your hand.
Next, you'll grind down the head or the screw using a bench grinder, hand files, or sanding disc in your flexshaft, whatever you have to use. Work until you have taken off the top of the screw and the slot for the screwdriver is gone. Keep a dish of water nearby to cool the metal while grinding.
Use sandpaper or files take off all the tool marks and clean up any sharp edges. Don't polish, you want a little tooth to help prevent your tool from slipping.