G scale coal pile

This is a G scale model coal pile that fits into the POLA coal bunker. It is printed in a generic black PLA that I still had lying around.

Update: After 2 months outside in the garden and in the sun, the PLA did deform a bit. The edge of the coal heap pulled away from the surrounding walls by 2 or 3 millimeters. This is not a big deal for me, because it is only visible if you are almost directly above the coal bunker. If you want to avoid this problem, then you should use other filament, e.g. PETG.

STLs for both coarse and fine coal is attached. The STLs are actually quite hight (~50mm), I moved them a bit below the buildplate to get a shallower print (see 3MF file).

The SCAD file can be modified to get other sized if needed:
* xx and yy are the size of the base
* zz2 controls the height
* the difference between zz1 and zz2 controls the steepness of the pile
* stepmax and steppart control the coarseness of the particles
* seed is the start-seed for the random numbers

The SCAD file references the library af-basics.scad which can be found here: https://www.printables.com/model/175914-openscad-library-for-more-basic-shapes