Well, I just thought they would be a good idea, and whenever I have a good idea I can be sure that someone cleverer than me has already thought of it, so I googled 
Curiously, I just came across these whilst looking for something else, which could be good for anyone with a 3D printer:
They are on this website: http://www.hybridpretender.nl/ towards the bottom of the page.
Yes, I have hand held radios with different gender SMAs which can be a nuisance. One of the cheap adaptors that I use fell appart, and has been soldered back together - so I can recognise that one without finding my specs and peering down the end!
73
Adrian