Use APKPure App
Get Darkroom Negative old version APK for Android
Turns your phone into a darkroom negative.
You need a darkroom with an enlarger which can fit your phone to use this app. If you don't have such an enlarger, it is simple to build one for $30 - just search "Darkroom Enlarger for Phone" on instructables.com
1. choose a picture from your gallery
2. choose exposure time
3. click play
4. CLAP! to begin exposing the negative