Ever since the Power Functions components were released, I've been trying to build a shunter similar to the scale of the 9V collection's shunters. I had some self imposed rules: It must be as small as possible.
I cannot modify components (Parts, PF electricals)
It must have a driver's cabin: you must be able to place a minifig inside.
It must have forward facing windows (Driver needs to know where he's going!)
Loosely based off the British Rail Class 08, I've been toying with this for a while now but this is what I've come up with. (Sorry about the bad photography) Driver has standing room inside the cabin. He has to share it with cables, but it's comfortable enough. Works well both forward and backward. Power button is easily accessed by taping up the tiles on the roof and the entire middle panel comes off. The reciever is in the middle of the cab, with a small slot for recieving signals. Despite its sunken nature, it's still quite responsive. The battery sits up front, providing its weight to the front wheel. It sits as low as possible by having the motor's bogie pin sit directly into a tube on the bottom of the battery box. The cables of the motor loop around the gap in between. I don't see why a set comprised of a small train like this can't be offered for sale at a lower price point. On this model, the only discontinued (irreplaceable) part is the forward facing windows, but a substitute can easily be used by removing the doors. Thanks for looking. Criticism, name calling and abuse welcome!