Temple Institute menorah

Recently I was zoche to visit Eretz Yisroel, and my family went on the Temple Institute (Mechon Hamikdash) tour, very interesting. They showed their beautiful menorah, which they said had been made according to halachic specifications and could be actually used when the Beis Hamikdash is rebuilt, בב"א. I was very surprised when they said it weighed half a ton - as I know that the menorah must weigh a kikar (talent) of pure gold. Not clear how much that is, but something around 50 or 100 pounds (see Wikipedia, and Rashi's calculations at the beginning of Parshas Pikudei). Not even close.
So I went to their website, and they have an extensive description of the issues involved https://templeinstitute.org/history-holy-temple-menorah/. Kol hakavod for their clarity and transparency. What they said astonished me. Short version: It is hard or impossible to make a strong enough structure of pure gold, especially such a small amount as a kikar. Instead, we made a bronze menorah weighing half a ton. Then we took a single sheet of gold (mikshah) - a millimeter thick (!) - weighing a kikar, and wrapped it over the bronze support structure. That gold is the golden menorah; ignore the bronze underneath.
a) This seems like a cool trick, but I didn't see anyone mentioning this pshat in the Torah. It does not sound like the simple understanding of what Moshe Rabbeinu did (the Midrash mentions that he found it difficult to know how to make the menorah!)
b) The Rambam says (Beis Habechirah 3(4)) that when other metals are used for the menorah, it may be made hollow (חלולה). When made with gold, on the other hand, it sounds like "mikshah" excludes its being hollow; it must be made solid. I saw that the Likutei Halachos on Menachos 28b brings the example of the menorah made by the Chashmonaim when they reconquered: an iron structure coated with tin. You would not be allowed to do that with gold, and that is exactly what they did.
Comments?