(Disclaimer: I enjoy playing KSP.) Then any escaped "fine metal powder" could turn into a 10,000 km/h sandblast for the next satellite over. It'd probably be

(Disclaimer: I enjoy playing KSP.) Then any escaped "fine metal powder" could turn into a 10,000 km/h sandblast for the next satellite over. It'd probably be fine for the ISS, since it's in a low enough orbit that dust should deorbit quickly, but you'd still have the basic issue of logistics. I can't comment on how convenient it'd be to build and operate a 3D printer in hard vacuum, beyond "not very".