Building Gadgets is a mod by Direwolf20 that adds several tools that make building in Minecraft very much easier.
[You can read the official wiki for the mod by clicking here](https://github.com/Direwolf20-MC/BuildingGadgets/wiki)
All Gadgets need RF to function.
Hold the mods's Settings button (G by default) to open the radial menu:
The radial menu has all the different settings for the Tools. On the Building Gadget, each of the buttons on the circle are a different building mode, the buttons on the right are options for that building mode, and the buttons on the left are for manipulating the world.
Building Gadgets will remember the last 10 times it was used, and you can undo them with the Undo button.