My SmartrapCore from SmartFriendz is really cool, but the cables inside the box are kind of messy and, since I installed the Bowden extrudeur inside the box, and the filament is coming from the roll that is just outside the box, there's a friction between the filament and the box border.
I designed this small and simple piece to resolve both problems : it holds the cables on the right side inside the box, and works as a guide for the filament, to keep it at a not-too-bad angle, and away from any friction with the wooden box.
The hole that guides the filament is curved just enough, and the inside diameter and widening in and out openings let the filament slide really smoothly.
The cables can be put in the holding part by gently bending the piece, and I made holes to screw it to the wooden box (10mm thick), but mine holds just fine without any screw.
And yes, there's a little bunny on the front. I put bunnies on my designs now, just for fun. :)
Update (07/30/2015) : I added a smaller version that only helps the filament to slide around the box border (no cables holding if you don't need that).