Wherever you live, winter lingers. The days are still short, the nights are long, and weekends…well, with the whole family stuck together in the house, they can seem almost endless. To help you wile away the indoor hours, we asked Asia Citro, founder of the blog Fun at Home with Kids, to share this great craft that will occupy your kids for hours and hours—if not days and weeks. It’s infinitely tweak-able so as soon as your preschool and elementary-age brood tires of one iteration, you can break the whole thing down and start again. Or set to work building a whole robot army!