the author of this app says:
tinyGL is a very tiny 3D modeling software. This second distribution has added several new features, such as multiple models, export, undo and an off-host viewer.
The handheld isn't really designed to do stuff like this, but if one sticks to the basics, it might work, at least for fun.
Still, don't expect to do large landscape models with tinyGL, though you could make a model with around 100 vertices.