[Kaiyou]

Absence of evidence isn't evidence of absence. A good training exercise I can think of is to build complex Lego models according to the instructions. It's how I spend lots of my time in my early childhood, before I was allowed to play video games and watch TV. By touching the pieces and rotating them yourself you get good image training of how shapes look when you rotate them. Building things in a 3D space based on drawn instructions from only a single point of view should also help to build mental images.