Truck

My kid likes to push 'vehicles / ships' he built with Lego bricks on the floor, creating screeching and unbearable noises which will invite neighbours' complaints. I created this very low profile truck, i.e. thin, with 8-pins to connect to bottom of the 'vehicles', coupled with wheels which are printed in flexible material, managed to solve the noise issue when pushing the bricks around. Critical portion includes form and fit, i.e. dimension accuracy, rigidity of part, and there's a portion with snap-fingers. Hence the truck is printed in 100% infill and ABS. In case your nozzle has worn off, the parts will be printed with 'more plastics' causing parts to become tight fit (against other Lego bricks, etc.).

Caution: Wheels are small parts and when printed in flexible material, can be mistaken as candies, parents with small children are to take note. Once snapped into the truck, it is not likely the wheels will dropped off.