This is a load for a 34ft Athearn hopper car. The 3D-printed part can be used as-is, or weights and scale-coal (or other material) can be added.

The part includes two mounds. These are intended to make the load look more realistic/add character, whether or not the load is covered in scale material.

Two different STL files are provided. One has just the final part (in which case supports will likely need to be generated during slicing. The other STL file includes six extra volumes that can be used to support the part when printed standing on one of the short edges (see pictures).

The part can accommodate self-adhesive tire weights, which will increase the weight of the hopper to NMRA spec. The weights are placed on a "fin" below the load in order to put the lower in the body of the car.

There are two notches in the load so that it does not interfere with the hopper's middle ribs. These notches are not particularly visible if scale material is added to the top of the load.

When viewed from the top, the load is not quite rectangular. It's wider in the middle because the hopper itself also is.

In hindsight, the part should likely be strengthened by converting some of the middle support to be actual part.

Creality

Ender-3 v2

Yes

If using the STL file that includes supports, all the volumes can be moved together in CURA by first "grouping" them (right mouse click option). Don't forget to indicate to Cura that the six extra volumes should be printed as supports.

Especially if scale coal (or something else) is not going to be added, consider printing the "top" of the load with Cura's fuzzy skin setting. One of the pictures compares versions of the load printed with and without fuzzy skin.

Printing the part with the included supports worked well for me. Printing the part with the load side facing down did not work at all. The associated slicer-generated support could not be removed.

After printing:

• The top of the load was painted flat black. This is likely more important if not adding scale load material.
• Self-adhesive weights were added to bring the car up to NMRA standard.
• A small metal reinforcing plate was added to the center of the part for increased strength and to potentially enable magnetic removal of the load (this did not work out).
• Scale coal was glued to the top of the load with dilute PVA (white school glue). A wax paper collar was placed around the load so that the coal could be put on very thickly to ensure coverage.