ogeecrew@jeandiv14 Hi there. The difference is only cosmetic. MJF parts will be slightly stronger and better surface detail. Thanks for the question.
Natural: This finish has a slightly rough surface and a matte finish
Processed: This finish removes some material to create a smoother surface
Premium: This is our smoothest finish with good scratch resistance
ogeecrew@davide6 We initially designed the LazyBone with a integrated stem-cap, but discovered that the nylon material deforms over time, when put under constant stress (which is the nature of the stem-cap function). If Shapeways offers aluminum in the future, we would bring the integrated cap design back. Thanks for the question.