unsub wrote: None of the local scrap yards want to have anything to do with offloading copper.
Not sure I understand you, the local scrap merchant near me has 6 large bins of copper. I started going in about 4 weeks ago and in that time those 6 bins are full to overflowing with every type of copper you can imagine, and they sell it for just under $10 a kilo... I got 1¾ mts of 2" for $18 last week. It looks like it was an old exhaust of some sort, very easy to clean. I sealed one end and filled it with hydrochloric acid... 2 litres cost $10.50 at Mitre 10 (it is reusable).
The beauty of buying old copper is that you can be pretty sure its not thin cheap "Made in China" stuff.
For an end cap I went to Repco's and got a 2" welch plug. Mitre 10 have a lot of reducers, but 2" end caps are $20... hence ny preference for a welch plug which was about $2.50 from memory.