Ikea train lego wagon

Easy to print, just drop 2 neodymium magnets in the holes, superglue a 2x8 thin Lego plate in the top cut out and screw the 4 wheels loosely for them to rotate freely. If you leave to little clearance in the wheels it won't turn nicely, especially in the 90 degree bends.

Screws should be stainless steel or brass so that they don't attract the magnets given that they are relatively close. Wood/chipboard 3.5x16 mm countersunk head recommended.

Magnets should be cube or round, doesn't really matter. Maximum size is 6.5mm. Once inside it will self align to the magnet on the next wagon so it will never repel :-)