This is how I made a 80×120 cm dollhouse for my 2 girls by using basic tools and paint colors from their rooms I already had . I used cheap softwood (pine) and glue + nails for the joints. I had a initial plan created in Sketchup and I sticked to it with minor changes.
The result isn’t 100% perfect but it doesn’t have to be, to give your babies endless fun and make you happy for that.
Router (not necessary)
Circular Saw (not necessary if you buy the wood precut)
Lot of Clamps
30cm width pinewood
Paint colors (already owned)