This enclosure is not 100% waterproof but can reasonably survive rain while protecting your smartphone. This enclosure was used over a 5 day period including two days of rain and easily kept the camera dry.
Using this enclosure, you can take time lapse videos like this.
Step 1: Parts you will need
2. A few scraps of 1" thick wood or plywood
3. A smartphone with a time lapse application and built in camera
4. Small tripod
5. Charger cord for the smartphone
6. Miscellaneous screws