I used part of the "Laundry App UI Kit Sketch Resource" design that was designed by Satheesh Kumar at: https://www.sketchappsources.com/free-source/3397-laundry-app-ui-kit-sketch-freebie-resource.html to create a quick prototype

3 different counters using variables 1. A standard counter 2. A counter from the number of seconds the user sets 3. A countdown

Online Fashion App Project

Basic To Do prototype based on: https://www.sketchappsources.com/free-source/3625-basic-to-do-app-design-sketch-freebie-resource.html

Interactive TV app prototype of Hulu's home page. Use the arrow keys on your keyboard (note: mouse click to enable keys) or map to a remote control on a television screen to explore a Hulu like home screen with proto io. Note: Must click the canvas to enable key presses, this seems to be a common restriction with most prototyping tools when building key press focus interaction models.

Shopping cart using variables to calculate selected item amount, and total costs using variables. Project also includes a thumbnail gallery

One Page Website example created with Proto.io