Round Copper Downspout Pipe... Worth anything?

[Clifford]

Our local building supply store has some round copper downspout pipe on sale.

It looks like it is about 3", round.  It has a crimped seam on the back, and crimped on one end

I think they're asking about $20 per 10' segment.

I've been thinking about buying some for solar water heater panel experiments, and soldering, welding, or brazing the back seam.  However, getting a good seal on fittings might be a problem.

Thoughts?

[DanG]

When dealing with copper it is the metals thickness gauge that is important - if its not new-old-stock it most likely resembles foil.

Even worse is if it is copper-plated aluminum - that $20 tag is in aluminum 3" round retail price range.

If a single three-inch 10-foot section weighs eight to ten pounds buy them, that would translate to 16-oz per square foot 'gauge'...

Edit: At scrap prices here the 10-pound 3" tube would fetch $37 so something is definitely up there.