Here's a crummy little cell phone photo of a template , just after the housing was cut. The base is just 1/8" hardboard, and the walls are 1x1 maple (whatever you have laying around). The fence is about 2x2, and is a little longer than the template on each end for clamping. Always clamp to the reference face, of course. We do not use a top bearing bit. The base of the router runs along the walls of the template. We use 1" diameter router bits, that are 1-1/2" or 2" long - easy to sharpen, as you don't have to fuss with the bearing. We do cut out the center of the template using the router. The clamps are Irwin Quick Grip. We like those bacause the sides pop off so that you can blow out the sawdust that can accumulate in there and jam the mechanism (other brands are glued together). As someone is sure to point out, the templates are specific to one diamter of router bit and one size of router base, in our case, the 3HP model from Makita (3612). We have 3 in our shop. CB.