Tendrils are twisting, threadlike structures by which true climbers, such as grape vines or cucumber vines, grasp an object for support. Vines with tendrils will climb on their own, without being trained.
A model aeroplane is used for presentations and testing. Model planes are also used for fun. They are used model-plane clubs, aeroplane company headquarters and studios. (Bedroom, in my house)
The only answer that comes to mind is "Airships". Hydrogen, the lightest element, was used in airships, where excess weight was undesirable. However, accidents like the Hindenburg disaster showed...