3D line drawer

I was looking at hecatris' build and was thinking: "Hey! I can try and make something like this with command blocks!". Haven't actually finished anything but a device that draws a line in between two points (you select the 9-th hotbar slot for a second to summon a special zombie, the cursor, and then you put a villager somewhere else in a 128 block radius from the zombie to draw a line in between those two)

I also noticed that if you spawn ~3 zombies and let them wander with no target (no villager) they will build cloud-like structures.