***I think I know what a Necker cube is...but in a different dimension !***
Different from what? The name 'Necker Cube' is really a misnomer. It should be called the 'Necker Projection'. That is because it is really not a cube (3D) but a drawing (in 2D) of a particular projection of a cube. So, there are two different dimensions involved and these might be confused.
***I like that impossible pitcher...Should we depict these as optical illusions?***
Yes, absolutely. That's the whole idea. It is easy for us to draw 2D pictures on paper and it is just a little less easy to construct 3D figures in wire or plasticine, but there is no known way of constructing a 4D or higher figure. So, what we can do is construct 2D or 3D figures that give the "illusion" of a 4D figure. These could correctly be called "optical illusions".
***Do you need a supply of them?***
No, but thanks anyway.
***I can put some borrowed ones on my website if anyone asks.***
I would be very pleased to visit your web site. What is the URL?
***Second thought, can a person ( such as I am ) draw a picture of this in 2-D and then build it from my box of plastic straws ( have 1000s !) and placticine?***
Yes. Of course it depends on what you mean by "this".
***Are there different rules for workplace safety in different dimensions?***
Yes. The rules would be vastly different.