Dual SIM Switch Widget was the first free app that gave us ability to toggle our SIM cards on and off, as well as mobile data, using simple widgets on our home screens. Plus, schedule. Plus, option to skip weekends.
No further development
This project was abandoned on January 18, 2015. App stopped working properly on devices powered by Lollipop and I didn't fix it... Originally, I made this app for myself. I liked the fact many people used it, but I couldn't have committed to it.
It was designed for most dual SIM phones based on Mediatek chipsets, but not all. If it works on your dual SIM device, I'm glad.