@ps2270 I changed the translation thus:
Molding promptly and reducing a hollow form to a relief</head>
<ab>You can imprint the relief of a medal in <m>colored wax</m>, & you will have a hollow form, in which you can cast <fr>en noyau</fr> a relief <add>of your sand</add>, on which you will make a hollow form of <m>lead</m> or <m>tin</m>, in which you will cast a <m>wax</m> relief. And then on that <m>wax</m> you will make your <tl>mold</tl> with a hollow <fr>noyau</fr>, to cast there the relief of <m>gold</m> & <m>silver</m> or any other <m>metal</m> you like. But to hasten your work if you are in a hurry, make the first imprint & hollow form in <m>bread pith</m>, prepared as you know, which will mold very neatly. And into that, cast <m>melted wax</m>, which will give you a beautiful relief, on which you will make your <fr>noyau</fr>.</ab>
1) I translated "hollow form" which is how "le cave" has nearly always been translated as per our most recent discussion 2) I did not insert "And into that cast there" as you tentatively suggested – it sounded much more clunky than in the French
Let me know if I should make further changes.
re point 2., perhaps "And into that, cast in melted wax" might be an option. Keeps the redundance but is slightly less disturbing.
Yes, let's translate as you suggest in your last comment.