The largest issue I have seen so far using this mod is having a defensive position when building on a planetary surface or in an asteroid. You can't defend your base, essentially you dig under someone, set up one of these things and bam their base is yours with little to no effort. Even if you have your own build and repairs, the attacker's nanites have a edge in the race against grinding the two systems down.

Making nanites ONLY pass through stone while picking up or welding would solve this problem. As it stands there is literally no way to defend against these things building on a surface, I know I lost two bases to that tactic and you can't really feasibly set up mines around you when you are first starting out building >.>