These machines are inherently dangerous. Before the machine moves, the machine should be clear of any person by a dimension of at the distance of a persons reach plus a few more feet. This is the policies we institute in our shop and what is recommend to all of our customers. Treat these machines as you would treat any major power tool in the shop.
With that said, you can certainly add some protective parts, but still keep folks away even with those installed. I would use the gantry side to do all of the mounting of the protective parts. Consider using sheet metal that you can bend and make a simple installation right on the gantry side.
Click the link to add information to this solution:
THESE MACHINES ARE DANGEROUS, WHAT DO DO?