I can dig up some shots of medium complexity type pattern routing...but you are limited by the size of the router bit (1/4") and the collar (add 1/16") and you can't route sharp inside corners. Anything finer in detail needs to be done on a scroll saw or with some other small tool. Routers can do a lot of different types of cutting...but getting intricate details is tough. Again the scrollsaw would be better for the job. Conversely you could also cut your side panel hole entirely with a saw...but that leaves work marks all down the edge...which is why I was suggesting routing holes in panels to get a more finished look.

So in essence you could use the router to do 9/10ths of the work of an asrtistic window and then transfer the pattern to the panel and cut the rest with a rotary tool or a saw. Your intial drawing will have to be modified to allow for the strength of whatever you are cutting. A simple example being any closed loop letter or character like a "P" needs to have that center portion bridged to the body of the letter or it won't be there...and you cannot leave too little material or it will bend or break...then you have to try and incorporate all those structural elements into the aesthetic part of the drawing...if you get my drift. Or else your stuff will look like a stencil.

That is when a waterjet or lasercutter is really the right way to go.