In a large pot, melt butter over medium. Add marshmallows and cook, stirring, until melted, 5 to 6 minutes. Remove from heat and add popcorn, toffee, almonds, chocolate chips, and salt; gently fold to combine.
Working quickly, lightly coat hands with butter and gently shape popcorn mixture into 16 balls; place on a parchment-lined baking sheet and let cool until set, about 10 minutes.
Store in an airtight container at room temperature, up to 4 days.