I have been experimenting with my vision for a motor to go inside the torso, so that Barbie can be attached to the end of a rod which moves through the neck. The two wheels are made of mdf with ply rims and the drive belt is made from an bicycle inner tube. The motor is a 12v 15rpm motor but I can change the rpm by varying the input voltage as I want Barbie to appear and disappear quite slowly. The metal shaft on which the large wheel is mounted has two skateboard 6mm bearings on its fixed mount to minimise resistance.
I have also had to rethink my donations boxes. I had thought the glass maker down the end of my road would make them inexpensively, as he talked about it being an easy job and he would glue them in place. However, his quote is way beyond my budget, so I am making them myself, with 8mm clear acrylic. They are standing on beach offcuts from a work surface, 500 mm high and 22 mm wide, with a mesh top to which I am attaching various devices.