There are two built-in timers in Marvin: a sand timer and a tomato timer. Turn on the timers strategy (☰ 🡒 Strategies 🡒 Timers) to get quick access to the timers.
When you turn the strategy on, you'll be asked how you want to access "Timers" within Marvin.
Opening the timer dialog
Click the timer button in the Skinny Sidebar to open the timer dialog or press "T" on your keyboard to access the timers from anywhere.
Timers can be set anytime and are visible at the bottom right.
Changing the timer sound
In the strategy settings, you can choose if you want to hear a sound when a timer starts/ends, and if so, which sound will be played.
At the bottom, you will find a volume slider where you can adjust the sound volume.
By clicking on this icon when you hover over a timer, you can pop-out a timer which will make it appear above other windows on your desktop.
For example, you can see a timer while you're going through your emails: