Draw out a ghost shape on a piece of wood. I just made a long arch shape for mine. And kept each one somewhere between 3 and 5 inches. This can be any type of wood your like. And works great with scrap wood as well.
Use jigsaw to cut wood ghost shape out.
Sand the wood. To make the wood smooth and free of splinters, you'll want to sand the shape you made in step 2. You can you a power sander or do it by hand with a sandpaper block.
Attach wheels on one side to dowel rods. You'll do this twice, so that you have two sets of wheels started. So one dowel and one wheel. And then another dowel and another wheel.
Wait for it to dry and then cut off any excess dowel rod. Using a multi tool or pull saw, cut any dowel rod off that is sticking out from the outside. Not the inside long part. Cut the outside short part.
Now that half of the wheel sets are complete, determine where you want the wheels to go. Mark them off with a pencil toward the bottom of the ghost shape (or whatever shape you created in step 2). You want to make sure that you don't mark the holes off too far down OR too far up. Because that could effect how the wheels will run on the finished car.
Use a drill to create the two holes that you marked in step 6. You want to make sure that the two holes you create are LARGER than the dowel rods you are using. They don't need to be significantly larger, but at least one or two sizes bigger. That way, the wheels will run smoothly when the project is complete.
Thread the dowels through the holes. This one is self explanatory.
Add glue to the inside of the wheel hole and some to the sides of the dowel as well. And then put the dowel through and add some more glue around the dowel and wheel hole if necessary. THIS PART IS MESSY.
I threaded the dowel through so that the majority of was sticking out the other end to get the wheels closer together. You'll cut the excess off in the next step.
Just like you did in step 5, after the glue is fully dry, cut off the excess dowel rod that is still sticking out from the wheel.
Hand sand (or power sand) any excess dried glue and any remaining dowel sticking out from the wheels.
Paint the car and the wheels, if desired. And then add a sealant to finish things off. Now, your tiny ghost toy is ready to ride. *You could also paint the base of the car before it's all assembled (so after step 3). But for the wheels, I would wait until the end, because you might have to sand off excess glue. So, I just did it all at once, at the end.