Decided to make a bigish red lorry (19x13x16 cm). Its mostly felt with some nice traffic patterned material on the side and red gingham on the bottom. I used some clear PVC for the window so its sort of looks like glass. The number plate on the back reads HPP 2010 (happy plush plush).
It was a bit of an experiment but I think it turned out pretty charming. Its up now on in my etsy and dawanda shop.
Thanks to Ciaran for the help with the photos.