Where to purchase insert tubes that go between plastic shelves?

ask the manufacturer who would sell them.

1 1/8 inch pvc seems hard to find. Can you use a size smaller?

Can you tell us what it's used for? That would help a lot.

I searched all over the web but had no luck in finding anything plastic. Could you possibly find wood dowels at a home improvement store the correct circumference and have them cut to the right height?

You might check on ebay or amazon or someplace like that. We threw all ours out, if I had known a couple months ago you could have had them! Someone might be willing to sell some tho....2nd hand stores? Good will?

If you can find vacuum accessories, the extension rods work. I just used pipe tape around the bottom and top to beef up. Good luck.

I would substitute wood dowels, shower rods, curtain rods. copper pipe. Some spray paint. There has to be something that will fit.

My only suggestion would be to contact a plumbing supply co. and/or an air conditioner supplier, they might be able to steer you in the right direction. And that is a very unusual size, I see where you are having trouble finding that size.

Best of Luck

sorry, maybe check amazon they supply alot of items

Could you just drill through a 1" pvc pipe and use a hefty nut and bolt as a stop?

I would wrap the 1 inch pvc with one of those plastic shower curtain covers.

try https://formufit.com/pages/pvc-pipe-size-dimensions-chart

Unless the tube is completely bad, cut just past the break and cut the others to match, making a short shelf.

Could you replace with timber?