You shall overlay it with pure gold is identical with verse 11. And make a molding of gold around it is almost identical with verse 11. See the discussion there on molding.

And you shall make around it a frame is literally “and you [singular] shall make for it a rim encircling.” The word for frame means something that encloses, like a “border” (Durham, Fox), but it is to be a handbreadth wide. This would be approximately “3 inches wide,” or “75 millimeters.” Translator’s Old Testament interprets this as “a strip of wood” that goes around the table, and New Jerusalem Bible pictures it as “struts,” or braces to make the legs sturdy. It may be thought of as a structural support connecting the legs about half-way down and extending all around the table.

And a molding of gold around the frame uses the same word as verse 11. This molding was probably just a decorative “gold border” (Good News Translation) that was added to the three-inch frame, or “rim” (Good News Translation). So one may say, for example, “Make a strip [or, frame] of wood 3 inches wide to go around the table and fasten it to the legs. Then place a gold border around the strip.”

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .