With the accent on safety, it is compulsory at many Clubs for the tips of transmitter aerials to be marked/protected, in particular, to prevent eye injuries. Not impressed by plastic golf balls or film containers stuffed onto the aerial ends, I searched for an "engineering" solution to the problem.
Certain plastic bottles have large spherical caps - could one of these be made to fit? Yes, very simply! Just use the neck of the bottle, suitably trimmed, as a nut. This tightens down on a disc of ply or plastic, slotted to slide over the top section. Packed to suit your aerial and bottle cap this provides a very solid fixing with the added advantage over other methods that the aerial will close up completely on many transmitters, minimising the risk of bending the thin top section. The diagram alongside should make it all clear.
The cap doesn't have to be spherical, so any suitably sized cap can be used - the use of a small one would enable a light foam polystyrene ball to be attached but still be removable. Colours : Preferably white or a Dayglo colour, but for 27Mhz the channel colour is acceptable (but problematic unless you NEVER change frequency).
Easy isn't it! And this will make you more welcome when you visit other clubs and events.