I signed up this week to the mailing list of Kids Craft Weekly. On their website in the 'free printables' tab was this really cute printable for a digger with moving parts. Here is the link if you want to print one for yourself.
I printed the digger onto some white card, then printed a second copy and cut out the wheels so that they could be a moving part also. Jack painted the digger yellow and used brown paint for the wheels.