Flying models: See § 24c Federal Aviation Act
The operation of small flight models up to 79 joules kinetic energy (about 250 grams): e.g. mini toy helicopter, mini planes of foam (with camera) is allowed up to a maximum height of 30 m. Any danger to persons or property has to be excluded. Since there "flying toys" are excluded from the scope of the Aviation Act, they may be also operated outside of model airfields.
See § 24d Federal Aviation Act