Finished a the vent cover as @lowside suggested and @Tony inspired:
The Italian reads literally “discharge vent”. I toyed with the idea of translating Glowforge or even putting the whole thing in Latin, but this works.
This is cheap plywood so it’s a little splintery, but as a prototype it works great.
I kept one layer of the Celotex plug just to give it a little more insulation. It’s dropping into the teens tonight.
Makes a much neater fix. Still has that unfinished look all in all because of the Duct tape and wallpaper, but it functions perfectly.
I used this image of a Roman utility access panel cover. I went ahead and did the whole drawing from scratch with Inkscape instead of the trace and fix. It worked fairly quickly and that makes it much easier to repurpose.
And here is the bitmap to be engraved.
