Lego Train-Compatible Tanker Car

This is a tanker car that is compatible with Lego Trains and Train Tracks.

It has a magnetic coupler at each end that allows the magnet inside to flip to ensure proper polarity with adjacent coupler magnets. Insert one magnet into the slot of each of the two couplers. They are designed for a 10x2mm size button magnet. I ordered mine from Amazon "DIYMAG 120 Pcs 10x2 Premium Brushed Nickel Small Round Cylinder..." You may need to use a tool to push the magnet through the slot. It's intentionally designed to be tight to prevent the magnet from working its way back out. You can widen the slot, post-print, of course.
There are two options for the wheel trucks. The ones that end in "_Pin" use a 2mm x 45 mm stainless steel round shaft axle rod that can be found on Amazon. The ones that do not end in "_Pin" simply use M3 screws. The _Pin version has a lower rolling resistance, but in my opinion creates slightly more noise than the M3... not a lot though. The decision of which to use might just be determined by what you already have or can easily get. In the end, both options work fine.

Be sure to do a good job cleaning out the counterbores on the TankerCarFrame.stl. You'll want the cradles to be flush with the M3 screw heads that are used to attach the trucks (bogeys) to the frame. Once you are certain the screw heads are flush, glue the cradles to the frame using plastic cement. In fact, you'll use plastic cement for the brake wheels, the fall protection, the dome, the cradles, the end bars, and the ladders.