I put 2 elongated holes right under the bridge so that it is covered by the bridge itself. One hole for the left 3 cables and one for the right 3 cables. These holes going just in the maple carved cap, were probably 4-5 mm wide and 10mm long. In the area under the maple cap i just made a bigger routing channel that connected to the bridge pickup cavity. You want to plan these joining the bridge cavity at full depth so that the pickup never squeezes the piezo caples. Also make these a bit spacy so that you can 'fish' the cables easily from the pickup cavity. I actually made a little ramp but that would fall into the German Overengineering category. You also want to make sure that channel connecting the bridge pickup cavity with th electronics cavity is wide enough that it supports pushing these 6 teflon cables through. Keep in mind the 6 cables are thing, you need to plan for the black connectors to fit through. In my case I just had a dedicated channel, one for the bridge pickup and one for delicate piezo cables. If Rob is OK I can post some pictures here. But didnt want to hijack this one too much. And if you belong to the part of the world that believes in shielding, then you might want to shield that part of the cable channel because the piezo's are high Z. And talking about shielding, you cannot just ground the trebble body insert/post of the bridge stud as the saddle elements are non-conducting and will leave your strings ungrounded.