I agree it is vinyl, vinyl often has that texture.

You can just buy one online...the hole is a square, it was probably cut to a standard size. Look for drainage grates.

If he had a metal lathe yes. Clearly he's not a metalworker. But it was still possible he had a wood lathe.

I guess you could cut stainless steel tube on a wood lathe, slowly, maybe? But you'd have to make that plug to hold it on the lathe anyway, at which point it's faster to take it out and use it as your clamping jig on the cutoff saw. Not to mention safer

Screws and nails into end grain, never. That is super weak.

Glue into end grain... not recommended by master carpenters I guess but for holding a jig together it's fine. Especially if it's a short fat piece of wood like a chunk of 2x4. I've done it before, and when the glue cures, it's near enough unbreakable. It's not "super super weak" like you were saying... you're thinking of screws into end grain.

I hadn't bothered googling it, was just talking from experience, but since you rudely called me a googler I went ahead and found this video. https://www.youtube.com/watch?v=m7HxBa9WVis It shows that you can break the end-grain glue up at the glue joint, BUT it takes more force to break the glue joint than it does to break the wood on a side-glued joint. So I was partially wrong, the glue will break before the wood if you glue end grain to end, but it is still super strong.

>End grain joints are super, super weak.

They really aren't. They're a little weaker than a side-grain glue joint. Maybe.

Get a couple chunks of 2x4, glue them end to end properly with wood glue and clamps, and I bet you $1000 you cannot break that joint. The wood will break first.

Well yeah if he has a metal lathe he could just do the whole job there... I'm assuming he doesn't because nobody who owns a metal lathe would ask this question.

Good thing this is a sacrificial piece of wood that will get thrown out

Make a wooden plug that fits inside. Use a lathe if you have one, but hole saw, bandsaw, hand tools, whatever. Glue it to the end grain of 2x4, then you can just slip the tube over the plug and clamp the 2x4

Quick tip: if you're in a hurry and it starts acting up, you can press and hold the (wired) button... this overrides the sensor and lets you force it to close even if it's misbehaving. At least it does on mine.

Shelf is solid wood, looks nice enough, if you like the style.

I'd hang it with some angle brackets under the shelves. These brass ones come in a 4 pack for $3: https://www.lowes.com/pd/ReliaBilt-RB-3-4-IN-SB-CORNER-BRACE-4-CT/5001634841

Screw one side into the underside of a shelf with the provided brass screw, other side into the wall with longer screw. It'll hold 100+ pounds if you get 2 of them in a stud.

You could use picture-hanging hardware as others are suggesting, but eventually somebody is gonna put something heavy on the shelf. Also, someone could grab it for support.

Nobody ever regretted making a shelf stronger...