How was the belt attached to the Eifod?
Rashi and Seforno (on Pasuk 6): Refer to 28:4:1:1*.
Having said "ke'Ma'aseihu", why does the Torah repeat the same list of materials mentioned in connection with the Eifod?
Oznayim la'Torah: To teach us that the straps of the Eifod should be made of the same materials as the Eifod
See Oznayim la'Torah citing the Tif'eres Yisrael.