I think it’s quite difficult to do extended activities to practise the present continuous. The very nature of the tense means we are talking about things happening now which makes conversation limited. I find a lesson on the present continuous is often made up of a variety of activities.
One way to get around this is to base the lesson on paintings and what is happening in them. What are the people doing? What are they wearing? Where are they sitting / standing? What are they saying to each other? Etc.
You could start with pictures and sentences to describe the pictures scattered about. Students match the pictures and sentences. You could also use sentences with gaps for students to fill in. You can then focus on the grammar: how the present continuous is formed and when it is used. If the students are familiar with the present continuous, this stage will be brief. If it’s a new structure, spend more time on it. Students can then practise the structure orally by describing pictures in pairs. You could also follow this up with a writing activity.
You will also need to pre-teach the vocabulary for describing pictures.
I hope you and your students will enjoy this activity.