Use Google Slides! It is an awesome platform for collaboration and easy to use. Share a single Google Slides with your students so that all students are on the same Google Slides; each student adds their own slide. Create a culture for your class that "we are a community of learners who helps each other get better" so it is expected that students will comment on other students work. You also have to help students learn how to thoughtfully and respectfully give feedback. While not a natural skill, a necessary life skill.