Ball wedge test

Following discussion here https://box-stacker.artificialworlds.net/d/309-slowly-does-it/10 I did some testing.

@andy was correct. The ball can get wedged if the triangle is nudged slightly out of position. If you squint hard, you can see the triangle angle up slightly as the right ball gets stuck.

But also see https://box-stacker.artificialworlds.net/d/316-testing-ball-stuck-without-triangle