Custom R/C car

I would like to build custom R/C cars of different sizes (1:32 scale, 1:16 scale, etc.). The car will have a chassis, 4 wheels, motors, R/C circuit and electro-magnets to pull another dye-cast car (without a motor) along with it as shown in the video. The cars should be able to make left/right turns, move in forward and backward directions, climb and descent slopes (15 - 20 degree angle) together without loosing their coupling. The dye-cast car above the surface can be any off-the-shelf standard hot-wheels or matchbox (1:32 or 1:16) toy cars. I will bear expenses for all the parts and shipping that would be needed for completion of this project, the bidder should bid only their service costs. The project will be marked as complete once I see the prototype demo and the prototype is shipped and received by me.