Bicycle tires with tire liners and/or thorn-resistant inner tubes are available to protect against broken glass and other road debris, but if you have access to old bicycle tires, brake cables and a measuring tape you can make an inexpensive DIY armour that will protect your tires.
Instructables user mariano states that cutting the bead off an older bicycle tire and fitting that bead inside your regular tires between the tire and the inner tube will protect you from 80 per cent of punctures, which is a cheap and easy solution. If that isn't good enough he recommends lining that cut off inner tire with the metal tape from a retractable tape measure.
The metal tape will act as an armoured barrier between your outer tire and the inner tube. The author recommends using the thin strand of wire from a bicycle brake cable to sew the measuring tape to the cut tire as using regular thread or dental floss will probably result in those materials being cut by the measuring tape. I'm curious to see how duct tape would hold up.
If you're looking to avoid bicycle tire punctures and Kevlar tires aren't in your budget you may want to consider this method. Any protection method you try will increase the weight and decrease the responsiveness of your bicycle somewhat. Note that the photo above is the tape on the cut bicycle tire that goes inside your actual bicycle tire.
Armouring a bicycle tire for final puncture protection [Instructables]