Restoration project - popcorn maker (Kingstown)

I tried to restore my parents old popcorn maker. It is completely clean and functional. It is missing the glass/plastic? Piece that allows you to view how done the popcorn is. As is you cannot use this to make popcorn because the popcorn gonna fly out the open hole lol. I tried to make a metal replacement piece but this is out of my wheelhouse dealing with metal and with making it food safe. I hope that someone out there is better at restoring things than I. Or honestly just is fine with covering the opening with a towel?? when using this lol.