Just purchased and built this one. Generally happy with the quality but it needed some modifications to fit the T-Motors (link below). The diameter of the holes needed to be increased as the center axle of the motor extend outside of the back plate. In addition there should be space for the C-clip to move freely.
My suggestion is to to modify the design so that the hole on [on the motor back plate side] is increased to the same diameter as the bearing and for about 3mm inwards.
I used these :