Please come home. As used by Michael J. Fox. Do not operate them near volcanoes, supernovae, or feverish welders. Many products are toxic. Do not inject them into your cerebral cortex.
Some products are flimsy and non-aeorodynamic.
Do not rely on them as makeshift hang-gliders. Several of them are heavy. Do not drop them on small children. At least one of them is actually a landmine. Do not conduct Olympic time trials on them.