Finding prefabricated stick insect cages is a challenge in itself, but trying to get one for a specific species of insect is even harder - if at all possible. Thankfully you can use inexpensive supplies from craft or home improvement stores to create a custom stick insect cage for your beloved insect or alter one you already have to best suit your stick.
Plastic sheeting and netting are two popular insect cage materials that can be purchased from a variety of suppliers. You can then use lightweight wood or plastic to create a frame for the cage in whatever size you choose. Home improvement stores sell all sorts of inexpensive trim pieces that are already thin and lightweight and that can be purchased by the foot. Beginner insect enclosures are usually fish tanks but as the owner learns more about their specific species they tend to gravitate away from the aquariums.
Many new stick owners start out with a basic glass aquarium tank because it is cheap and accessible. While fine for some insects, sticks and mantises need more space to climb on.
Some companies have websites that offer very fine netting that are good for caterpillars and other small insects. The mesh or netting allows the cage to "breathe" better and provides your insect with a much larger area to climb and walk on. If you often find your stick insect climbing on the screen top of his current tank he would probably love a cage made entirely of netting!
Screen door and window screen material that is found in almost any home improvement store is also great for many insects. Rolls of this material can be purchased as well as pre-made windows that some people attach together to create a cage.
There are many kinds of plastic sheeting available if you just look around at various stores.
Plastic food wrap is very thin but can be layered and wrapped around a plastic or wood frame for small insects that require high humidity. The clear plastic sheeting used for protecting your furniture while painting is a thicker, but still lightweight option. It is more ideal for larger insects and mantids that still require a high humidity but make sure to leave small holes or slits for ventilation - you don't want to suffocate your stick!
Many people will put the thicker plastic sheeting over a netted cage to still allow the insect to grip but would like a bit more humidity than an open netting cage offers. You can make one, two, or all the sides out of plastic sheeting, depending on your humidity needs. Again, if you decide to make the entire cage out of plastic, be sure to leave a portion open for air circulation.
If you are looking for more of a heavy duty material to build a cage out of, consider plexiglass. With plexiglass you don't have the fear of poking holes in the cage like you would with the plastic sheeting or food wrap, but you get the same high humidity effect for your insects. Plexiglass can be drilled safely, unlike glass that shatters easily, doesn't need a frame for support, but is also more expensive than plastic sheeting. You can attach the pieces using special glues or caulks, or with screws by drilling holes.
Overall, the species of insect, humidity requirements, number of insects, and several other factors need to be taken into consideration before building your own cage. I am a fan of the prefabricated mesh cages with plastic sheeting wrapped on all the sides, with the top left free of plastic so a door is accessible and oxygen can circulate, and the bottom open to allow any debris to fall out of the mesh cage.