1d20 — dice tray

Tap a shape to add a die, then press Roll. Hold Roll for advantage; press ? for the rest.

The tray

Tap a shape: Add that die. Hold it to take them all off again.
Roll: Throw the pool. With nothing picked, a d20.
Hold Roll: Advantage, disadvantage, the modifier, and the pools you saved. On a keyboard, press O.
Swipe the felt: Throw in the direction you swiped.
Drag a die: Move it. Let go while moving to flick it — it rerolls where it lands.
Clock: The last twenty throws.
Sliders: Colours and finishes for the set, sound, and rolling by shaking the phone.

Saved rolls

Pick some dice, then save the pool here.

Sound

Shake to roll