Baclofen (Lioresal) may be administered orally or intrathecally (introduced into the space under the arachnoid membrane that covers the brain and spinal cord) for control of spasticity due to neuromuscular disease.
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...