On Sep 23, 12:02 pm, wrote:
I have considered making a radar reflector that is inflated via a
helium canister just like a CO2 one. It would be like a balloon but
inside would have a corner reflector type radar reflector of
aluminized mylar. It would be attached to a pfd with monofilament so
it could rise to about 30'.

I also considered making a similar inflatable reflector that would be
mouth or air pump inflated for boat use. You could deflate it easily
for storage and it would be weighted so it always hangs in the correct
position. However, a Brit company already makes such but I have seen
one.