I've seen quite a few people make their own. Not sure how common using an old controller and wiring it yourself is though. But making the actual box, adding artwork, or whatever else is pretty common. They actually have ready made PCB's for this stuff now that are compatible with multiple systems, so technically I could have saved myself dome effort, but where's the fun in that?

It's actually 98% finished now. I did all of the paint and clear coats. The only issue I'm having is the stuff I wrapped the buttons in covered a small section of the top by a button, and the coats are a little light right up against them. There was no real way around it though since the PCB is right under where the buttons are. I'm going to hit Canadian Tire in the next day or two to see if they have any of the touch up pens you can buy for cars in the colour I need. If not, I'll have to spray some paint on something else and use an old paint brush to put it where I need it.

Compared to the detail work on some of the models I've painted, painting up to the edges of the buttons should be a snap.