Foolestroup,
If you are in Victoria, check out Aerolyte in West Heidelberg. I think David Long has now retired but I know that they kept the important dimensions of every instrument for which they ever made a case, certainly until I left Melbourne. My brother is probably one of only two concertina players most Chewton locals have ever heard of and doesn't use the net. He used to play in Smith's Gully and the other concer player around Castlemaine used to play in Tipplers All.

John,
In Australia we don't use ABS pipe for sewerage in any of the states/territories I've lived in so I can't comment on it but for stormwater drainage, sewer (black water) and other (grey water) household drainage we use PVC of slightly different sizes so that stormwater pipes (used for rainwater catching) can't be connected to the others by mistake. In smaller diameters it's also used for electrical conduit. But you're right about the other stuff. And one advantage is that its surface is slippery enough so that it would probably escape conveyor clutches better than the cardboard map tubes you often see.

Your comment about corrugated cardboard and airdrops reminded me that, years ago (we're talking 1960s now), bushwalkers who wished to spend extended times in SW Tasmania were allowed to send in airdrops of dehydrated food. Jim English was the favoured pilot out of Cambridge (the general aviation airport at Hobart) and he'd take the door off his Cessna (or whatever it was) and fly off with someone in the back who, on instruction, would heave the item out while Jim flew over the drop-site.

In the Mountaineering Club I belonged to at uni, the father of one climer had been responsible for getting medical supplies into the Kokoda Track during WW II and found that the best way to do it was to get large cardboard map tubes (they didn't have PVC pipe then), attach tin fins on the back, solder up a tin "nose" on the pointy end and fill the front with egg cartons. Egg cartons in Australia are generally papier mache with the usual humps & hollows for the eggs giving a three-dimensional 'crush' opportunity. A swag of these could be loaded into the bomb bay of a suitable bomber and dropped very accurately; even glassware was protected by the egg cartons. Using this info we packed a couple of layers of egg carton around the 20 litre (4 gallon to UK residents, 5 gallon to US resident) drum in which the tucker had been packed. This protected the tucker from even a direct hit (80+ knots airspeed from 200') onto a large rock. Of course, now that we're ecologically sensitive we don't do airdrops into Tassie but John's right about the crush resistance of cardboard in such shapes.

These days, the only other musical reference I have for egg cartons (just to cope with accusations of thread creep) is that a room that has its walls and ceiling lined with them is almost completely anechoic and (especially if painted black) a bit of a status cymbal for kids' garage bands

Cheers, Rowan