You will need the following parts:
Several cardboard toilet paper cores
Clear plastic packaging
A washable marker or highlighter
A medium sized paintbrush
Some sort of paint
Step 1: Cut Out the Base Components.
Coat the outside of the cardboard segments in Mod Podge and wrap a layer of aluminum foil around them. (see second image.)
While these are drying, go root through the trashcan until you find a discarded plastic package. I used the flat part of a package that contained headphones. From this you will cut lenses using one of your toilet paper cores as a cutting guide (see third image). Make sure to cut inside your guide lines so the lens wont be bigger than the eyepiece (see fourth image.)
Now take one of the remaining cardboard tubes and cut it in half length-wise and round off one end of each half (see fifth image.)
To make the bridge of the goggles, cut yet another cardboard segment in half length-wise. Using a cardboard segment as a guide, mark a half circle on one of these and cut everything inside that half circle into tabs (see sixth and seventh images.) Make sure to cut out room for the bridge of your nose (see eighth image.) (NOTE: I had to use a cardboard segment that was a bit longer than 2 inches as I have a wide face.)
To make rims for your goggles, you can use polymer clay, PVC, milk cap rings or any circular object that will fit over the end of your eyepieces. I used black polymer clay. I made a donut shape out of clay and used a cardboard tube and a cookie cutter to fashion 2 rings (see ninth image). I then baked the rings according to the instructions on the package to make them hard and durable.
That's all you need to make them. On to assembly...
Step 2: Paint.
Then, paint everything but the bits wrapped in foil and the lenses black or whatever color you prefer (all other images.)
Step 3: Glue.
Begin by gluing the rims to one end of your eyepieces and gluing a lens onto that (see image one.)
Then add the rounded cardboard halves to the sides of your eyepieces, making sure that the rounded side juts out beyond the eyepiece a bit (see second image.)
Once these are dry, glue the eyepieces into the bridge (see third and fourth images.)
Glue in a peice of cardboard on the back of the bridge piece for added support (see fifth image).
Now that you have completed the basic construction, you should coat the whole thing (except the lenses) in a thin layer of Mod Podge for added stability.
Step 4: Finishing Touches.
You will need to add a strap of some sort to keep them on your head. I use elastic, but you could use leather, rubber, metal or whatever you want.
Now you can start adding objects to your goggles to make them look more interesting. Just about anything that you can find will do. I chose to add one thing to illustrate my point. I found this extra RCA cable in a box of junk (see first image.) I chopped off the connectors, painted them silver and glued them to the sides of my goggles (see second and third images.) My RCA connectors may look a little cheesy but you get the point. Some other ideas you might use:
Snip the heads off of some small screws and glue them around the rims for a more mechanical look.
Use wiring and small components from an old motherboard or broken electronic device to glue on for a futuristic look.
Spray the whole thing in metallic chrome paint for a mad scientist look.
And so on.