This piece I made in Aluminium, using the same welding/grinding technique to get a nice bevel on the edges.
I used 25mm X 50mm RHS and TIG welded some pieces to blank off the ends.
This piece bolts into a notch in the top of the star, the plaque holder is riveted and glued to this.
I used bolts to connect this piece because I didn't want to weld the star. I wanted i to look like
the star was just snugly holding the piece in place.
The plaques holders themselves were made from 3mm aluminium sheet with some aluminium round bar in the corners, screwed in from the back with countersunk screws.