I think you should be able to run a pipe though the corner where 4 blocks meet.
It is also possible to drill glass with water cooling and the proper bit.

Has anyone done this? Or, how about acrylic blocks? The drilling part I mean.

Thanks for your help, great idea.

I've done some work with acrylic, and it can be difficult to drill. Regular drills dig in too fast and can cause cracks, but thick blocks may not have this problem. You can get drills with special angles for acrylic. You have to drill or cut slowly or the material will melt and stick to the drill or saw blade. Then it binds up.