Hey Wout,
I would always see an enclosure for a cnc machine that works on wood as a necessity, mainly because the debris of broken bits flying around is a serious danger, but because of dust and noise also. But since the ball screws of the Onefinity CNC machine are, as all oiled mechanics, totally incompatibe with wood dust, which is why on professional machines in the industry, they are enclosed in bellow covers, and the ball screws on the Onefinity are not, and the many enclosures shown in this forum cannot protect the oiled mechanics like balls screws from the wood dust, there is a problem for which the enclosure cannot help. Ball screws get literally destroyed by the wood dust. So the first question is, do you have a strong and powerful dust extraction that avoids dust where it is created, i.e. as close to the milling bit as possible? I would not save on that. And it eleminates a few subsequent problems. I would always think of the enclosure as the second thing, after best possible dust extraction.