First go into to the Yahoo group and ask if any of the vacuum formed shells are being offered as there are a couple of hobbyist that can pull them.


Second, you will want to get the car and electronics for it. If you want it to be as screen accurate as possible you will need to order up a Bolink Legends R/C car. You can order a new one from here or try to locate one on eBay. This is a quality hobby class car, and replacement parts can be ordered  from the manufacture or compatible parts found in hobby shops (unlike a car from Toys-R-Us or Radio Shack). Also with this Bolink car it is easier to get more clearance for your ride height, with the other cars you really can not really do so. Also, depending on your weight it could cause your droid to tip over easy with the cheaper chassis.

Next you will need to look at the electronics, I suggest dealing with a radio that is on 2.4ghz spread spectrum. The reason for this is you never have to worry about someone being on the same channel as you. This keeps you from loosing control of your droid or damaging someone else's droid. A standard 2.4 ghz radio will work, but a computerized 2.4ghz radio can help in setting the top speed of your droid, so you will not over power it. I can recommend you this system if all you are going to use this radio for is just the mouse droid. You will need a standard servo like this to go along with it. If you are going to think about building a R2-D2 and want a radio that you can use for both then I would suggested using a 2.4ghz airplane computer radio that is at least 6 channels such as one of these four units.

Hitec

Spektrum

Spektrum (higher end model)

Futaba

Here are ideas for a motor, motor controller, and batteries & charger.

1. If you do not mind having to maintenance the motor some you can go to a system like this.
2. If you want a maintenance free system then look at something like this. This option will also create less heat in the motor and the battery, making them last even longer.
If you have a hobby shop close to home you can talk to them about a possible cheaper solution, if you are lucky enough to have a friend into radio controlled cars you might be able to even get something used.

Batteries, I use 4200mAh NiMh Sub-C batteries for long run times. The higher the mAh rating, the longer they will last. This should be a good budget minded battery pack, but it is a no name brand.

Venom

Associated

DuraTrax

Integy

The good thing with a mouse droid is that you are driving at low speeds, so you are not going to be very taxing to your batteries, this should also help keep the heat down.

Here is a good budget battery charger that won't let you down, you can power it from your home wall socket, or a 12v automotive car battery (under the hood of your car if you are at an outdoor event).

You will need some simple tools like the ones I liked below for this build. You might even have some of these tools already, or a friend might. To help you visualize I am going to link you to Harbor Freight for the tools, they are rather inexpensive at this store as opposed to going to places like Sears, Home Depot, or Ace Hardware. Keep this in mind, you will not be doing anything heavy duty for the most part, so do not worry much about the tools lasting, they should all be fine for this project, and last you for most everyday type of stuff. The most you will be drilling into is 1/8 inch aluminum for most of the project. If you are going to make the top parts and do it so that it is just about screen accurate then you will need a couple more items, but for now lets concentrate on the main part of the droid build.


Here is the tool list:
1. A simple dremel kit.

2. Protective eye wear
(These are a must when working with a dremel.)

3. Screwdrivers

4. A simple 1/4" socket tool set.

5. Hex Keys both American and Metric
(I prefer these types because if the tips go bad you can use the cutting wheel on the dremel to cut off the bad parts and your tool will still work fine.

6. Respirator Masks (You will want to wear these if you are dremeling through anything creating a powder like carbon fiber , plastics, or wood)

7. Some extra 1/8 and 3/32 drill bits (for metal)
(These sized drill bits will fit into that dremel/rotary tool I linked you to above and you won't need to buy or borrow a drill.)

8. hot glue gun with a handful of glue sticks

9. 1/8 and 3/32 screws with washers and lock nuts
(I personally find these at Ace Hardware however Home Depot and Lowes should have them as well. I get them in a hex drive type, but get whatever preference you like: hex, phillips, flat-slot drives.)

10. Sticky back velcro

11. Aluminum angle stock (Ace Hardware, Home Depot, or Lowes should have this rather cheep).
Think about getting this in 1.25" x 1.25" x 1/8" or as close to it as possible.

Start by assembling the car chassis and installing the electronics, motor and servo to get a feel of how this should all fit into your shell. Use the instructions that came with the Bolink car chassis, and the electronics. Use fun tack (that blue or green putty used to hold posters or pictures onto the wall) to hold the motor controller and servo in place. Do not put the wheels on with the hex screws just yet, as the car chassis will not fit into the tray with them on. 

Then use paper to line the lower half of the mouse droid shell on the inside, use looped masking tape on the bottom of the paper to hold it in place, you want the paper to also come up the sides of the tray. The idea here is when you place the car chassis inside the shell you want to have an idea on where to cut the plastic out. (Tip, use a pencil to make your pattern so that you can make corrections.) When this step is done place the tray to the side and read the next section.

You will notice that the car is a bit different in size compared to the lower shell, so what most of us in the group suggest is that you take the front end off on the car chassis off and mount it directly to the outside front of the shell. For now when you remove the front end you will place it into the inside of the tray to get an idea of how to trace it onto the get the and cut the chassis in two.