Best ways to start a thermite reaction?
The method I've used is a simple propane torch, which you can get at Home Depot for $14 and magnesium powder. The mixture of powdered aluminium, iron oxide, and magnesium is thoroughly mixed and then lit using the propane torch. It lights all the time with the magnesium embers burning brightly and then the main reaction takes hold. Getting powdered magnesium is cheap as well. Using this method, the reaction takes all the time and I haven't had a single problem with it the numerous times I've done it for an audience.