Dead easy, dead cheap.
Tools and bits needed;
Old CD case, set square, small pliers, hobby knife, sandpaper, some Cocktail sticks, thin Card, needle, some woodglue, plastic glue and paint. (oh, an some spare wheels)
To make the struts for the sides, use the pliers to gently "snap" them off. Best to score the plastic at least three times for very thin pieces.
Basically, the toothpicks are cut to length, two for the shafts and one for the axle.The shafts I made by removing one side of the toothpicks to give a flat surface to glue them to the base.
All in all it took just under an hour to make this one and cost...? Nothing?