Can an array of small mirrors focus enough sunlight to melt steel? A solar furnace works by bouncing light from many mirrors onto a single point. The more mirrors you add, the hotter the focal spot becomes. You cut or buy small mirror chips about 2 cm across. You mount each chip on plywood with silicone and a toothpick spacer. The spacer lets you tilt the angle. Screws beneath each chip allow fine adjustment. You aim each mirror at the same target spot using one central mirror as a reference. A small 6x6 array is safe for learning the process. A larger array of 256 mirrors or more can reach extreme temperatures. A 4-foot by 8-foot array could create a focal spot 4,000 times brighter than normal sunlight.