Fuchi Kashira construction techniques

[Jesse F]

I am curious as to how the raised rims around the edges of a Fuchi/Kashira are implemented. I see this feature on several sets but have not been able to locate any information on how this is pulled off traditionally.

My guess is that the Fuchi starts off at the thickness of the rim, and then one would remove material to lower what will become the background, leaving the rim at the edges. 
It also appears in some images that perhaps material is removed more around the edges to create the rim, leaving more of a domed background area. I really see this on the Kashira where the rim and corner transition look to be the same dimension, and then cut at an angle towards the edge to create the rim.

Am I on the right track here?

[1kinko]

The easiest method is to solder the rim on and use a low carat gold rim or mask the shakudo and guide the rim alone (fire gilding or electroplating).

[Jesse F]

15 hours ago, 1kinko said:

The easiest method is to solder the rim on and use a low carat gold rim or mask the shakudo and guide the rim alone (fire gilding or electroplating).

I’m familiar with the gilding technique. Soldering the rim on was not something I had considered. 
In the example I posted I’m not so much concerned with the rim being gilded so much as its construction. I see several examples with the raised rim which appear to be part of the piece, rather than a separate part added.

Thank you for the reply!