I got an Olympus Varimagni angle finder (the old OM system one, from the 70ies) to take measurements. I designed an adapter to mount it on the E-M1 family cameras.
Here you see the Olympus Varimagni (left) and the Olympus VA-1 (right), both with E-M1 family adapters.
More about the adapters on my Angle Finder page.
Both adapters for eyepiece and angle finders for the E-M1 or E-M1 II will also fit the E-M1 X. The already existing adapter designs will fit on the new camera.
You may find out more about the adapters here:
Eyepiece for wearers of glasses for OM-D cameras
Angle Finder Adaptor for the OM-D E-M1, E-M1 II and E-M1 X