Inspired by the tubes from Portal of the same function.

This image is designed to fit into this background (https://goo.gl/g13COr), but it will fit well into any background of similar perspective.

The bottom half is transparent, but the top half is opaque so you can spawn the cube there without it looking obvious.

And while you're at it, why not download the cube I designed to go with it: https://goo.gl/yqrOoZ

Credit me by linking back to http://pancakebobapps.wix.com/apps in your credits section.