Liked ScubaStevis' design, but wanted to tweak it a bit.
Version 1 - I changed the location of the filament slot as the filament catches in the slot at the front.
Version 2 - I increased the length of the arm as I feel the original is too short. This is the version I like best. (Deleted this version as replaced by V.3 below.)
Edited 26/12/2017 Have updated the long version guide. (V.3)
I have made the hoop part smoother and made the clamp part tighter where it clamps to the rail. Also as well as the left side slot version, I have done a version with the slot on the right side.
First layer 0.35 then 0.1