Step 1: Materials
So the tools and materials are pretty straight forward.
-a clean tin can
-Copper gas tubing. (or a thick guage copper wire)
-Soldering Iron, solder flux, and solder wire, (preferably lead free)
-Bench vise (Not shown)
-You may want a heat resistant glove for the soldering
Step 2: (Build the Handle) Bend the Tubing and Flattening the Ends.
After this is done clamp the rest of the tube in the vise and make two more 90 degree bends to creat a mug like handle. Keep in consideration how far the handle must come out to accomodate your fingers and how far it must go down to accomodate your fingers. My cup's handle lengths were around 2 inches and even that fits my fingers like a tea cup.
once your done the last two bends measure out the length of the tab that you flattened earlier and make another 90 degree bend. mark the measure length after this new bend, cut at the mark, and flatten that end so you have another tab. (I'm better with visuals I'll point out what I mean in the picture below.
Step 3: Soldering
Take your handle and coat the bottoms of the tabs in flux. Now for the tricky part.
I started by touching the tabs to where I wanted them to be soldered so a bit of flux rubbed off on the area. I tinned those areas with plenty of solder then by holding the handle in place I pressed the soldering iron on the top of the tabs so the heat conducted through the copper tab into the solder and the can. After holding it in place for long enough the solder underneath melted and lightly joined the handle which allowed me to work on each tab and add some more solder (albeit sloppy) to make sure the handle stayed in place.
After this is through wipe off any excess flux and thoroughly wash, and dry the inside and outside of the can.
Step 4: The Cup Is Finished
Now fill it up with your favourite beverage and enjoy.
I wouldn't use a dishwasher on it though I don't think the solder would hold up.