A big round train track around the Christmas tree, and all the little foam houses in Christmas colors. Maybe even repaint a wooden train set to be Santa's train. IKEA HACKS - glue foam houses to IKEA wooden train track
"Tsumiki" chalk building blocks by a Japanese company. This is such a cool idea for kids to design there toy with chalk and then redo it over and over again. I bet you could chalkboard paint wooden blocks and DIY.