Here's my first completed conversion project - a plastic static kit modified to fit a slot car chassis. Starting point is Tamiya's Kubelwagen Type 82 kit:
It has a fair few pieces although of course a number of them (e.g. axles and wheels) are not required.
The model is 1:35, a little bit smaller than the 1:32 Scalextric scale as you can see from the chassis and underpan in the photo below:
So the chassis needed shortening and trimming, the axles were cut down, and the underpan had a hole cut into it for the motor (leading to the unfortunate thumb injury...). After building the model and completing the chassis, this is the state before final assembly and painting:
And the finished article, painted up for use in North Africa:
In the original model, the driver's door is open and the driver is facing out of the car with one foot out. After some delicate surgery, I repositioned his legs so he could properly sit in the car to drive it around the track.
The next project is a British equivalent to race against!