A little while ago I read a how to on melting
metal in a microwave. So having more money and time than sense I figured it was
worth a shot.
First I needed some safety equipment for this job: 
Here we have some metal tongs for grabbing the dish the metal is going to
melt in, some gloves that can hold hot things, and a face guard to prevent
molten meal from showering my pretty boy looks.
Now here is the general setup: 
Microwave plenty of distance from anything that can catch fire, safety
equipment ready to go, and a fire extinguisher in case things get out of hand.
As per the instructions I fashioned a brick kiln in the microwave. 
The brick under the steel bowl is
silicon carbide and should provide a nice hot surface to warm the bowl.
In addition I sealed off the entry and exit vents of the microwave to try
and get the inside as hot as possible. We do not want our hot air flowing out
the back. 
Bricks with holes in them was not ideal, but it was what I had to work with.
The metal to melt is zinc: 
Yup, I hand cut that with a hacksaw and it took a ton of time to do. The
melting temperature of zinc is 786.2°F. Supposedly the max temperature you can
achieve using this microwave strategy is 900°F-1000°F so it should be possible
to get the metal up to melting temperature. Fumes from molten zine are
relatively harmless, but if you breathe too much it is possible you can get
metal fume fever.
The long term effects are negligible, at most it seems to produce flu like
symptoms for a few days. Here is a material safety data
sheet if you want to know more. Of course we are going to need a mold for
our molten metal: 
A bit rough, but should work. This mold is made out plaster of paris with
wood blocks to give the plaster a form to mold around. Of course I broke it
getting the wood out so its been put back together and secured with a rubber
band. Nothing else to do but fire it up and wait. I turned on the microwave for
about an hour and here is the result:
buttons…
I was unable to achieve a high enough temperature. The metal and bricks were
certainly too hot to handle, but I had no temperature gauge so I have no idea
how off from the melting point I was. A couple things contributed to this
failure:
1. After 30 or so minutes the microwave front became loose reducing its
ability to build up heat inside.
2. I did not make a full kiln with the bricks, and the bricks I did have had
holes in them making it harder to build up heat in there.
3. The microwave I was using was $5 and was made in 1993, it is possible it
just does not have enough power to build up the heat I need. Over time the
magnetron inside the microwave will weaken based on how much use the microwave
gets. Since I have no idea how intensively this 21 year old microwave was used
this may or may not have started to happen.
4. It was quite a hefty chunk of zinc. Perhaps things would work better if I
had a smaller block.
So things were a bit of bust, but I have not given up yet. I may try again
once I get some more bricks to build a better kiln. A better microwave might be
found at a yard sale or I might try doing this the old school way with
charcoal. It might also be good to try and get a baseline for this by melting
something with a really low melting point like solder (370°F).