Simple shapes that work best for DIY Halloween decor themes include bats, ghosts, pumpkins, and branches. Bats with pointed wings made from black paper create dynamic wall swarms. Ghosts shaped from white sheets or cutouts offer classic spooky silhouettes. Pumpkins can be mimicked with plastic milk jugs shaped with or without faces and lit from within. Branches arranged into wreaths or placed in vases add natural texture and frame focal points. These shapes are easy to replicate, renter-friendly, and visually effective when repeated in a cohesive color palette. Sticking with straightforward, recognizable silhouettes maximizes impact with minimal complexity, delivering stylish and moody decor that resonates with Halloween tradition.