Fotodiox has a new eyecup kit called the EyeVenger available for Canon DSLRs. The EyeVenger is designed with left and right eye cups (both are included) and ships with 18mm and 22mm mounting brackets to cover the gamut of Canon DSLR viewfinders.
[youtube https://www.youtube.com/watch?v=hPG_SybUNNU&w=700]The Fotodiox EyeVenger Eyecup Kit runs $19.95 and is available direct from Fotodiox’s website.
Any experience using this sort of eyecup? I’ve seen them before and thought they look like they may be more comfortable, but it’s hard to know.