Cut the dryer vent hose into three different lengths: 2.25 ft, 2.75 ft, 3 ft.
Paint each hose length a different color, using two coats if needed. Allow to dry completely.
Curl each hose back on itself so the ends meet. Hot glue the ends together, using binder clips to hold the hose in place until the glue hardens. For the smallest pumpkin, you may need to keep it clipped closed overnight.
Place the middle pumpkin on top of the largest pumpkin. Add hot glue where the "ribs" of the pumpkins meet to adhere them together. Repeat with the smallest pumpkin on top of the stack.
Create a stem and hot glue it to the top of the pumpkin stack.
Decorate the pumpkins as desired with leaves, flowers, ribbon, etc.