But it requires no more than a touch to reveal that - despite appearing solid - his amazing artwork can be stretched and twisted in every direction, before springing back to its original form.
The talented Beijing artist condenses up to 20,000 sheets of flexible paper to create everything from rocks to people.
"At first you don't think they could possibly move. But when you open it or provoke it, you discover a change.
"My sculptures can move, stretch, spread, twist and bend, contract, anything!"
Hongbo developed his mind-boggling style from the ancient Chinese art of 'paper gourds' - which takes hundreds of painstaking hours to perfect.
He added: "Some can take months to make - I go over every detail so nothing can go wrong.
"The centre has to be exact because the structure is flexible. It will tip over if the centre is off.