Just seen this which is even tighter.
http://s26.postimg.cc/3rqeewhcp/image.jpg

However he has got partitions which i think is a good idea.
Does that mean it's good.
Martin I don't often give negative comments but you seem to be blinkered I don't understand why are you asking questions and not taking any guidance there are plenty of reasons you need space. The Estop can be connect to the BOB but that is only controlling the emergency with software and is dangerous.

.
I suggest you read some of the excellent build logs on here to get an idea in what is needed to build a safe and reliable machine.