Modified MMU3 Selector R4

The stock MMU3 Selector tends to break when tightening the clamp that holds the FINDA in place. 

My first one broke, as it seems they made the hole larger than the previous model. 
I ended up remodeling a couple features on it. First, I made the clamp relief slot approx. 3mm deeper to give more material to spread the flex across. Second, I added an radius fillet to soften the intersection of the rounded clamp portion and the flat surface it connects to.

Add a radius and a deeper relief slot.