Great quality chassis - almost perfect
I chose this chassis because it has HC-SR04 ultrasonic sensor mounting holes. Not many do, you have to come up with your own solution. It also happens to be a very good quality plastic that won't shatter if dropped. I've used another chassis made out of acrylic that will break if dropped. This shouldn't. The slight issue is that that ultrasonic sensor mount doesn't include screws. If you want to secure it properly, you'll need to get some 1.5mm jewellery screws and nuts. These can be a bit hard to find. Another solution is to just use blu-tac or double-sided sticky tape or even glue. Still recommended for those wanting to build an ultrasonic robot, you'll just have to find a way to secure the sensor.
Leo