By attaching incredibly reflective foil to a piece of glass, or even another material with the dimensions of the mirror you want to use, a reflective mirror surface can be created. Tin foil which is bought in the supermarket is not quite reflective enough, so reflective foil insulation should be used for the simple mirror you are trying to create. This foil is like the malleable surface of a mirror. These come in roles and can be rolled out over the surface of a piece of glass, and either taped or glued down to the glass itself. Attached over a wood frame, the reflective foil insulation can be stapled or glued to the back of the wood frame.
Highly reflective mirror tape can also be used. This is easy to attach to a piece of glass, as this type of tape has a very strong adhesive on the back of it. This may lead to a slightly funky-looking mirror, as the tape strips are only so wide, and even if placed perfectly together---side by side and not overlapping---there will be breaks between each strip, marring the pure reflection in the mirror.
For some people, mixing chemicals together to actually silver a mirror might be simple, if they have the proper tools and chemicals at their disposal. The whole process usually only takes about three to hour hours and requires chemicals like silver nitrate, sodium oxide, ammonia and sugar, and a good heating and cooling surface. There is also an incredible amount of stirring involved when making the mixture. However, it is most important to do this in a well-ventilated or outdoor area, as the fumes that can come off the mixture can be very harmful to your health.