They appear to be solid. I bought them for my grandson who is 10-15 years old. He just wanted them to stick to the ceiling, but some stay on the ceiling for a few seconds and others don't stick at all.
๐ Playskool Chase 'n Go Ball Popper Active Toy: Fun for Babies & Toddlers, Includes 4 Balls!
8 Review
๐ฎ Infantino Sensory Balls Blocks & Buddies - 20 Piece Basics Set for Sensory Exploration, Cognitive & Physical Skill Development, Early Color & Number Introduction
7 Review
โฝ๏ธ VTech Bright Lights Soccer Ball: Illuminate Your Game with Fun and Learning
8 Review
๐งธ Fisher-Price Fun Rhythms Interactive Developing Toy - Bibel FBC98, Pink/White/Purple
9 Review
๐งณ Convenient and Versatile Kids Travel Tray: Toddler Seat Activity Tray with Art Supplies Storage Pockets
10 Review
Fisher Price FWY41 Animal Wonders Jumperoo
9 Review
Baby Einstein 4-in-1 Walk Around Discovery Activity Center Table - Ideal for 6 Months+ Babies to Promote Development
8 Review
๐ Enhancing Physical Development and Sensory Stimulation: Early Learning Centre Blossom Farm Playmat & Arch - Amazon Exclusive
9 Review