Mike, even though I've only seen a picture of this one it looked and sounded
slick.
Get ohold of some metal (steel, brass?) that has an ID that the ends of the
stove grill pieces that stick out will fit into.  Cut two pieces longer than
the distance of the opening.  Slide the tubing onto the open end of the
grill until it clears the opposite side then slide back onto the opposite
side.  Do the same with the second but it needs to under the first so you
will need to make a 'U' shaped bend in the middle.
BTW, I didn't need to do this, I scored a set of the VW logo inserts when
they were avaialble.  Gee, I wonder if they are taking on value like the
Munchkin ice cube trays??  :)