I've read and seen videos a few times of them nicking or breaking glass if there big enough and angry enough. I think acrylic would be something to keep in mind lol.
This is a rare shot of my little hitchhiker mantis. I've only seen him completely out a couple of times, but he'll poke his head out if I tap on the tank in front of his burrow. He's a Split-Thumb Mantis Shrimp (Gonodactylus bredini).
I don't have one, but if I did I would set up the tank similar to the one that shown in the video below, where the tank has a section where you can view the mantis's hole of where it lives, at 1:33 mins into this video. So very cool.
Mantis Shrimp are considered "not reef safe" http://www.liveaquaria.com/product/prod_display.cfm?c=497+525+1702&pcatid=1702
If you want one, you will need to provide it with a tank of it's own.
They are kinda pricey (IMO) because most of the ones I hear about are gotten as hitchhikers in newly purchased live rock & are removed dead or alive to be re-homed. Very aggressive little boogers!!