Adds a new research that gets you a third tool belt.
https://mods.factorio.com/mods/Thaui/four-toolbelts
It's not a duplicate. My mod adds one technology, your mod adds two. With your mod you can get three bars with green science, this requires blue science for that. I found the differences significant enough to also publish my version.
IF these were both used, could you get 5? Regards, ~B
Use these commands (or modified versions as apropos) to get up to 8:
/c game.player.quickbar_count_bonus = 3 /c game.player.force.quickbar_count = 5
Both gives 8 toolbelts