These tiny bats can be made from polymer clay or epoxy putty to decorate scale miniature or Halloween scenes. The bat shown has its wings outstretched for flying, but you can also make roosting bats using the same method, by shaping the wings to fit around the bat's body.
Before you make a model bat, try to find a photo you can scale to use as a measurement. Most bats are the size of mice with large wings, so they are very tiny for model scales. I managed to find one photo of a bat shot alongside a tape measure on the Batguys website. If you find a photo like this, you can reduce it's size to the scale you want to model in order to keep your bat an appropriate size for your scene, and use the photo as a template to check your scale.
Bats come in many shapes, sizes and coat and wing colors. Try to create model bats based on the shapes and sizes you see for real ones, your scene will be much more effective.
There's a great free clipart poster for International Bat Night celebrated on August 23-24th that would make a great backdrop for displaying your mini bats!