paper wheel wall rosette backdrop
FamilyFun's "spectral eyes": paint boxes midnight blue; cut holes; cover holes with yellow tissue paper; put a wire of fairy lights through (no bulbs outside the boxes) ... Maybe make luminaries like this that spell out Happy Birthday???
Photo 1 of 20: Scooby Doo / Birthday "Caleb is 4!!" | Catch My Party
Scooby Doo party banner in pink Instant Download by inkincgraphics, $5.00