Hobbyists have been building model cars for generations. Today is no different. A popular model nowadays is the low-rider, a large, older car that has had its suspension lowered so that it is almost dragging on the street. In addition, many regular size low-riders also have hydraulics that make the car's wheels jump and bounce. Model manufacturers sell hydraulics chassis kits that you can substitute in a regular model to make it jump and bounce like a real low-rider.
Open the model car kit and the model low-rider hydraulic chassis. Test the hydraulic chassis first to make sure it is in good working condition. You do not want to have to take the model apart later if there is a problem.
Read the instructions for your model car kit and your model low-rider hydraulic chassis thoroughly before beginning. When you build the model you will have to stop before attaching the body to the plastic chassis and instead attach it to the hydraulic one. Make sure you understand what the procedure will be for your particular model and low-rider hydraulic chassis.
Build the model car according to the instructions that came with the kit. Stop just before attaching the body to the chassis. Line up the body instead with the low-rider hydraulic chassis. If they do not exactly fit, use a craft or utility knife to carefully trim away the areas on the body necessary to make it fit. You will also usually have to trim away some of the plastic material where the parts attached to the kit's packing.
Screw the body to the low-rider hydraulics chassis with the screws provided. You can also attach the body using epoxy glue, which will require sufficient time to harden before you proceed.
Connect the wires from the hydraulics chassis to the control box according to the instructions. Some low-rider model chassis kits are wireless, so you do not have to perform this step. Test the hydraulics to make sure they still work.
Paint your model and apply decals as desired once the hydraulics are installed and working. Make the look model more authentic by replacing the model kit's tires with low-profile, low-rider model tires. You can make the wiring less noticeable by running it through the model car's body. You can drill a small, unobtrusive hole in the rear bumper so that the wires all exit the car at the same place.