Round pumpkins or squash with flat bottoms, such as kabocha or Italian stripe, make great vessels for plants. Cut off the top third and hollow out the bottom two-thirds, leaving about an inch of flesh all the way around. Add a small amount of potting soil, then arrange succulents inside. Fill in any gaps with more potting soil. Use a small paring knife to cut a thin layer off the rim for a clean look. When the pumpkin or squash is past its prime, repot the succulents.