Geocache container with the use of PET neck. Cut the neck of the bottle 3 millimeters behind the large ring. Use glue (preferably two-component epoxy) to glue this neck to the body of the train. Stick the locking ring on top. Then glue the axles for the wheels (smallwhellconector and bigwheelconector) to the body of the train, put the wheels on them and secure with glue a pin (bigwheellblock and smallwheellblock),
The length of the inner space is 90 millimeters with a diameter of 20 millimeters for the logbook.