At the current time, the camera view of the image on the bed can be off by up to 1/4" at the edges of the bed. There is a fisheye effect with the camera that has to be compensated for by an algorithm.
So what this means to you, is that if you are trying to cut out accurately around something that has been drawn by hand or printed with ink, it’s going to be harder to do it accurately if you place the item to be cut out at the far edges of the bed.
You will get the least distortion of the image right underneath the lid camera, so try placing the artwork and items there.
Another thing that you have to be aware of regarding that algorithm, is that it relies on a very accurate measurement of the height (thickness) of the material being cut. If you are using the Proofgrade materials, that information is included in the QR codes supplied on the material. But if you are using something other than Proofgrade, you will have to accurately measure the thickness of the material with a digital calipers, and enter that thickness value (in inches) into the Unknown Materials button at the top of the left column in the opened file in the interface. (You will also need to specify your settings manually for non-Proofgrade materials.)
Doing those things will enable you to get much closer placement of your design on the item that you are engraving.
If you want complete accuracy though, I highly recommend use of a jig. It allows for perfect placement.