I want one of these !
Not for me you understand, but as a part of my exhibition kit. The lady who owns it uses a wheelchair and as such struggles to see the scenic part of many high model railways layouts at shows. She bought this from an Italian company called Navir.
I was kindly allowed to have a quick go and the results are awesome. You look at a model and all you see is the model. Your field of vision is limited a bit in the same way it's limited by the wings of a stage set. This 'scope is wide enough that you don't need to squint through it either, the view is natural, 3D and apparently slightly magnified.
At shows I'd lend this to children so they don't need to be lifted up or balanced on barriers. It's not that I'm worried for the backs of the parents doing the lifting, it's just that ever since I saw a child plummet onto the catenery on a nearby display I've always been wary. Don't suggest a lower display either - I want to be stood up for easy chatting to visitors and that means the baseboard has to be at a suitable height for my 6ft 3 frame thank you. The periscope would made everyone happy and I bet even some who don't need it would want to have a go.
OK, so I can find out more information on this on the company website. I just need to find out where I can buy one from...