How to Make Thermite

U.S. Crow has a short article on making thermite devices. After explaining some of its uses and limitations, the author notes a few basic safety issues:

Thermite can not be used over recently ignited piles of thermite slag (waste matter separated from metals during the melting of ore), this will cause an accidental ignition and will cause severe burns and eye-damage.

TH3 can not be mixed by intention or fault with water. This will create a steam explosion and cause fragmentary harm to surrounding personnel. In addition, thermite should be handled with care to prevent accidental abrasion-caused ignition. All safety precautions during the production of a TG must be strictly adhered to.

Based on a Mythbusters episode on thermite and ice, it is dangerous to set thermite off on top of blocks of ice because it can cause an explosion.

As for the making, the article states:

The first thing you’ll need is aluminum powder, you can buy this from Amazon. You can make aluminum powder by grinding up soda cans and other aluminum items, but that could cause impurities in your mixture.

Now you need rust or iron oxide, you can buy this on Amazon or at any hardware store in the paint department. You can make iron oxide post-disaster by putting steel wool in a jar in water and covering it with more wool. Use a magnet to prevent the steel wool from floating to the surface. Now, add 5 tbsp of bleach and 5 tbsp vinegar. A day later place the steel wool paste in a coffee filter and let stand for eight hours. This is iron oxide.

The fundamental mixture ratio for thermite is 3 parts iron oxide 2 parts aluminum powder. Mix your 3:2 with 2 parts plaster of paris. Mix the three composite materials thoroughly. A well mixed composite will have uniform coloring. Add just over the amount of water required for the plaster of paris and mix thoroughly.

Once mixed you have a little less than ten minutes to pour your liquid thermite into the canister. Before pouring the mixture line canister with magnesium ribbon. You can also use thermite igniter fuses. Now fill the canister with the thermite. Set the canister in a safe place and allow time for the composite to harden. Larger canisters take a longer time to harden.

Additional thermite method: Another improvised method for thermite development with a low incendiary yield would be an 8:3 thermite mixture kneaded with 4 parts clay, and with a magnesium ribbon for ignition.

The author has links for purchasing specific products from Amazon on his page. He then goes on to describe the ingredients for making Thermite TH3, which has a lower ignition temperature, but apparently better suited for destroying materials.