The design consists of the features of shape and configuration of the POPCORN MAKER:Figure 1 is a top front perspective view of a popcorn maker with the lid up;Figure 2 is a top view of the popcorn maker of Figure 1 with the lid up;Figure 3 is a bottom view of the popcorn maker of Figure 1 with the lid up;Figure 4 is a front view of the popcorn maker of Figure 1 with the lid up;Figure 5 is a rear view of the popcorn maker of Figure 1 with the lid up;Figure 6 is a left side view of the popcorn maker of Figure 1 with the lid up;Figure 7 is a right side view of the popcorn maker of Figure 1 with the lid up;Figure 8 is a top view of the popcorn maker of Figure 1 with the lid folded down; andFigure 9 is a front view of the popcorn maker of Figure 1 with the lid folded down.