Welcome to CPF
:welcome:
Aftermarket implies a manufacturer other than SureFire, and I'm not aware of any entity big or small that offers an aftermarket TailCap for the E-Series that has a strobing 'feature'.
As mentioned, SureFire themselves do not offer such a thing although there are a variety of TailCaps and switch options available for the E-Series.
FYI, it is convention to refer to the E2D LED as "E2DL" to avoid any confusion with the incandescent version E2D. The same applies with other SureFires that are LED versions of existing products (6PL, Z2L, C2L, G2L, G2ZL, 6PDL etc)
I'm not sure what would be involved in designing and shrinking? the strobing feature into an E-Series TailCap form-factor. There are plenty of E-Series models that could make use of a such an aftermarket strobing TailCap. The electronics and mechanics for such a concept, along with the user interface (UI) to operate it could make an interesting discussion/project.
Al