I wanted to make this for quite a while.
Design is based on this:
http://www.thingiverse.com/thing:556896
http://www.thingiverse.com/thing:554724
I added the frame to fit the cone from above to 60D LCD screen.
The individual parts were glued by acetone.
The lens itself came from Coilcraft kit, ~10cm FL, 25.4mm dia (it could be anything of course, and parametric design should be adjusted accordingly).
From now on, I don't need additional glasses any more to clearly see what's on the LCD screen - which is very useful when focusing.
If someone is interested, I can post the files here.