Start the project, choose a shape, turn the object, click on the shape, then click on somewhere on the grid to start designing a D&D weapon with calculated statistics.
Disclaimer! This system is only intended for swords, axes or spear like weapons, so bludgeoning damage is not included. This project takes average statistics to calculate the most probable statistics for the weapon you have designed. I would personally allow my players to use this for custom weapons they would like to start with.