Line tray or cookie sheet with wax paper. Remove wrappers from desired number of peanut butter pumpkins. For each spider, cut 8 matching curved sections from pretzels which will form the legs. Set aside remaining pretzels pieces.
Place milk chocolate chips in a small microwave-safe bowl. Microwave at MEDIUM (50%) 30 seconds; stir. If necessary, microwave at MEDIUM an additional 10 seconds at a time, stirring after each heating, until chips are melted and smooth when stirred. Transfer to small heavy-duty plastic food storage bag. Cut off one corner of the bag about 1/4 inch from the tip.
For each spider, place peanut butter pumpkin on prepared tray. Attach pretzel legs and candy eyes to spider with melted chocolate. Allow chocolate to set before moving spiders.