Ultimaker internal axle end
This thing goes in place of the original wooden axle end of the ultimaker inside the body.
It can hold the 2x M3 nuts so it's a lot easier to fix the part (no more need to hold the nut with a twizzer or nut holder).
The hole in the center is also a little wider in order to limit friction on the bearing.
Works great in conjunction with thing 54075 for the outside.