where is a close up.
they way to do it is to make athe oval with reg poster paper....don't use something still, it wont follow the curves. you openin is slightly 3d. I would cut to just hit the edges.
you can buy coloerd electrian tape.
Since the grille block will only touch the edges, if it was me. I'd pop of the logo and get some thing round and hollow (toilet paper roll comes to mind) to brabe the center of the block to the grille. THen I would super glue the logo to the clear grille