Game Maker - Simple 3D Terrain Editor

Fall 2019: this is a suuuuuuuuper old version that doesn't work very well and has quite a lot of limitations. There's a new(er) version here, and I've got a third - and hopefully final - version here.

Make primitive terrain for your 3D games in Game Maker. Click around to deform or paint a terrain chunk with textures, then export it, view it in Model Creator and use it in your game!

I'm currently working on a better version, so if you like the idea but think the controls are a bit awkward or something like that don't worry, I'll hopefully have a new version soon-ish!

If you don't use Game Maker but think this is sort of cool-ish, Model Creator for Game Maker has an option to convert from d3d to obj (that may or may not actually work as intended).