Psiaic Pyramid

It doesn't have to be a pyramid, but that is the most efficient shape for traversing the Psiaic Dimension. More importantly, it is for some demented reason the only way to protect non-living materials being transported through the Psiaic dimension from being somehow subsumed by the dimension.
The rules of physics are different where this stupid dimension is concerned. Time functions differently, mental states get confused, and matter behaves oddly. There is a logic to it, eventually, but it nonetheless boggles physicists.
However, it is because of that difference that makes it so effect as a means to get items from point A to point B quickly. Or maybe just without outside interference since no one is going to try and rob you within the dimension.
The shapes are made of stainless steel, and have a compartment across the bottom filled with a specific chemical solution that draws the container through the Psiaic dimension to the end destination. You can put whatever you want in the storage compartment as long as it's not organic. 
It doesn't have to be an exact perfect pyramid, but the smoother the surface, the easier it goes. Not faster, easier. You're less likely to find cracks and dings at the other end if you keep it as smooth as possible.
The pyramid can be whatever size is needed, and the outer layer doesn't have to be terribly thick, either. The only stipulation is that the layer between the chemical propellant and the items being transported should be at least two centimeters thick. Not because the solution will eat through the metal or something, it's that it can leak through regardless when it's thinner and your stuff gets all goopy.
It works over almost any distance in the physical world, since you're dealing with an odd kind of space.