3DGE Builder is a modified version of Pascal Van Heiden's Doom Builder that is tailored specifically for 3DGE and Boom-compatible projects. This version features numerous changes to support 3DGE's level format as well as removal of all zDoom-based idioms and features. The only other capability it has out-of-box is the ability to create/edit Vanilla or BOOM maps, since 3DGE supports both.
The project itself is based upon MaxEd's fork, called [GZDoom Builder].
Setup and Configuration
In order to begin mapping, 3DGE Builder must be able to find and read the game IWAD. After launching the editor, go to Tools --> Game Configuration and under the resource tab, add an IWAD (either DOOM, DOOMII, or HERETIC)