Planned
Cube Rotate
The answer only works from one angle.
ChillNo failOne thumb
Bend the beam. Hit the target.
Place prisms and mirrors to steer a beam through a 3D chamber. Colours split, recombine, and only the right wavelength opens the door.
Design brief
More like this
The answer only works from one angle.
Escher, but you have to walk it.
Half these walls aren't there.