According to PipeDown :
A 100W soldering iron with a very large tip. These are also used to melt
lead caning for stained glass windows.

Uh, no. A soldering iron isn't hot enough to melt lead. You use ordinary
solder to join lead just as you do with copper.

It may be called a "Hobby soldering iron" as opposed to one for
electronic use.

These irons are usually for stained glass work. There are plumber's
irons, usually around 300W. Which you'll need will depend on the
copper sheet thickness and piece size.

There are also "soldering iron" attachments for standard propane torches.
If you buy a propane torch kit, it'll probably include one.

If you use a soldering iron (or a soldering iron attachment on a torch),
discoloring the copper sheet will be pretty minimal.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.