Common Accessories
I imagine some accessories which can be used with most or all of A-lights. I’d like to present them here.
1. Clicky tail switch:
This switch is not merely a mechanical lockout - UI should support changing modes with the clicky too.
If UI designer finds it beneficial to do a different UI for dual switch - it’s doable too as the driver can detect whether it’s powered with the switch or not.
How?
Technically the switch construction is based on GFS16 - FET for minimal resistance, power indicator, its own li-ion battery.
When turning on, the switch can make a quick pulse of power before actual full-on. This pulse can be detected by the driver (though this feature may somewhat increase the price).
Note: doing e-switch which would work like a clicky would make it like 4 mm shorter. But I guess dual-switch people don’t really want it.
2. Remote switch
OK, no drawing this time. 
A remote switch based on the clicky could be available as well.
3. Clip
No drawing either.
Many users require clips for EDC and I guess most A-lights should come with them, either stock or optionally.
Though the fins slope prevents sensible clip usage with larger A-lights. Maybe this should be changed by either removing those fins or adjusting the lights to use larger batteries? Or maybe larger lights just don’t need clips?
4. Diffuser
Turns all lights with 35 mm optics to poor-man’s lanterns. With way less cost, size and weight than a dedicated lantern, but worse beam shape too.