We have explained in our article Biblical Formatting that the Biblical Author indicates bullets by using repeating keywords. Hence we would translate Ex39-03 using a bulleted structure as follows: And they did beat the thin plates of gold, and cut it into threads, to work it
• into the blue, and
• into the purple, and
• into the scarlet, and
• into the six-ply linen,
the work of the skilful workman.

Hence the Rashi on Ex28-06b A separate and distinct gold thread is put into the blue threads and a separate and distinct gold thread is put into the purple thread and similarly for the scarlet and linen. Furthermore just as the linen was six-ply so too all the threads were six-ply. Each six-ply thread had one thread of gold a10ed to it making it seven-ply. The 4 seven-ply threads were woven together to make a 28-ply thread. The various priestly garments were woven from these 28-ply threads.

Advanced Rashi: Rashi is subtle here. The actual verse exegetical comment occurs on Ex39-03. However the Rashi comment is found on Ex28-06 which states And they shall make the ephod of gold, of blue, and purple, scarlet, and fine twined linen, the work of the skilful workman. In other words it is not clear from Ex28-06 whether there are separate gold threads for each of the blue, purple scarlet and linene or whether there is one gold thread woven with the 4 threads. Hence Rashi brings Ex39-03 to clarify and illuminate Ex28-06. Here Rashi uses the reference method. It is the repeating keyword into in Ex39-03 which emphasizes that separate gold threads are woven with each of the 4 threads.