Scribe the outline of the rectangle on the bbl flat you want to make.
Use any comfortable cutting V shape chisel or onglet shape chisel to then cut a border just INSIDE that scribed marking.
Give yourself enough room betw the scribed outline and the chisel cut line so that you don't get to near the scribed mark
when you get into removing the matr'l inside the cut border lines.
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Once you have the metal cut out inside the borders you should have a fairly clean border cut just shy of the scribed lines.
But it's probably somewhat uneven, not quite perfectly parallel with the nicely scribed line that you did with the scribe and a steel ruler
or a dividers.
Here is where you fix that and put the under-cut/dovetail into the sides for your inlay.
Take a flat chisel with a fairly wide face, not a small tiny graver,,more like a wood chisel size.
Use the wide face of the flat blade to punch the undercut into place.
At the same time carefully drive the same chisel towards the scribed line as far as needed to bring the box to the scribed border.
The bbl metal is soft. The chisel doesn't have to push the metal very far if you cut your border and inletted box close to the scribed line.
The wide flat edge of the chisel quickly brings the long lines of the inlet to square.
Corners can be done with smaller width chisel(s). Careful not to punch too far, and make an uneven line again.
But if you do, the metal you upset and raise when doing this is easily punched back down with a flat faced punch to push the border right back in position again.
When you feel you have the inletted box as perfect as you can get it, there will be raised/upset metal all around it.
Now take some 320 grit or close to that and back it with a file and carefully polish off the high, upset metal around the inlet.
The box will get filled with the black colored grit as you do this and will give you a perfect black & white pic of the box edges and any
imperfections. Fix any lines that are off.
That perfect B&W image you see is the same perfect image the inlayed metal will be. No out of shape angles, lines or corners if you take time to
prep the inlet right.
When satisfied, you can clean out the inlet with a brush, then I use a bit of alcohol or acetone.
Then lay the gold, silver, brass, copper, whatever inlay in place and punch it down into place.
It helps to clamp one end down while 'setting' the other end/edges so it doesn't grow and creep on you.
10k, 14k gold can be hard to work with like that, even 18k, Brass can give you problems., even silver sometimes.
Anneal any of them. But they work harden quick.
.....You can always just soft solder them in place!
