Printed from PLA on a Bambulab X1C printer. I recommend printing 0.2 layer. All supports.
EDIT: cubes and “body” of wagons held poorly, circle diameter increased from 9.5mm to 9.55mm.
EDIT 2: added stl and 3mf file(lego_duplo_train_base_vehicle_from 9.50mm_to_9.8mm_hole_chamfer) in case the first file(STL, 3mf) didn't hold fast enough on the wagon or with other cubes. (This happens when changing the brand or material of the filament). The change is in the chamfering of the upper part of the holes from 9.5 to 9.8 mm. Also added roundings.
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