I made a puzzle using the tessellating ghosts from https://www.printables.com/model/348163-tessellation-spirit-ornament.

I increased the size of the ghosts to x:47mm, and h:10mm (y-axis about 54mm) to make them safer and easier to handle for my niece. 

I made a base (and top) to keep the pieces organized. The top just sits on the base, so you will need a rubber band to keep it together.

I printed the ghosts one at a time with 100% infill with rainbow filament.