Here's two items that are beneficial in both new and existing CNC systems. The first is a table top mounted E-Stop to mount on your CNC for ease of access the way they should be. Table Mount E Stop Switch 10ft Shielded Cable | eBay
The second is Gecko G540 solderless motor connectors that make attaching your motors to DB9 cables a joke. They include mounting bracket which is also used for stress relief. hook up your motors or make configuration changes in minutes. Gecko G540 3 Solderless Motor Connectors | eBay