First off, I love the concept and I see a lot of potential here. So Kudos for that.
Bugs:
1. The belt laying didn't seem to recognize rail road tracks and placed ghosts over them that then led to a robot getting stuck waiting for me to delete the track so they could place the belt.
- For some reason, the belts laid using this tool don't seem to react to the the undo bottom (ctrl z) So, if you miss-click you have to then get out the destruction planner and destroy the belts before you can keep going.
To append onto what I said earlier about tracks. It had the same issue with a modded entity. Specifically Klonans transport drones roads Its a weird item that behaves like a tile, but prevents most everything from being placed on it...save for railroad tracks...hold up...Let me check on something...
So, after testing it out it appears that the mod transport drones is incompatible with your mod. I don't know what Klonan modified with the entities that can be placed on his roads etc, but it changed something that alters the tracks etc. I tested your mod without his and I didn't have any issues relating to the first bug...the undo function still doesn't work. (Transport Drones: https://mods.factorio.com/mod/Transport_Drones )
