Who doesn't love a marble run?  Those nice folks at Ravensburger have developed "Gravitrax", a fine line of marble run parts and accessories.  Because you can never have enough plates and pillars, I've 3D printed some clones of the parts that I run out of when building a track, and also some specials that are not in the official catalogue.

Downloads

Each part has an STL to download.  It is optimized for my Prusa MK4 with a 0.4 mm nozzle and printing at a 0.2 mm layer height.  The parts were modeled using Solidworks.

3D printed parts and cardboard

A stand-out feature of Gravitrax is the exceptional quality of the cardboard base.  The problem is that a close-fitting 3D print will tear the edges of the hexagonal openings in the cardboard base immediately on removal, so I've found that a 3D printed pillar, plate, or tower needs to always sit on a nice smooth original Gravitrax injection-moulded pillar when placed on the base.  No problem stacking a 3D part with another 3D part or standard injection-moulded part.

Pillars

The standard pillars are half-height 5 mm and unit-height 10 mm items.  Because my taste runs to long, slowly descending runs, I have STL models for two-thirds height 6.7 mm and three-quarters height 7.5 mm pillars as well as the standard 5 mm half-height.  These give height increments of 3.3 mm or 2.5 mm along a run, compared with the standard minimum increment of 5 mm.

Pillar

A non-standard pillar is the half-height "double-tie", intended to brace two tall towers against each other, or to brace a tall tower to an adjoining Perspex hexagon base.

Double tie 

Towers

A stack of 6 unit pillars can become a little wobbly (technical term, that) and a run of such also uses up a lot of pillars very quickly.  A 3D 6-unit tower replaces 6 pillars, and can also have an opening for a track piece to pass through.

6-unit tower with opening 

Other towers are 3-unit, 3-unit with catcher, and 3-unit with opening.

3-unit towers:  plain, with catcher, with opening 

Plates

A handy and relatively non-standard plate has two 120° curves, I found a pair in one of the Gravitrax advent calendar offerings.  More useful in the advent calendar were some sloped plates, entry at 1 unit height, exit at 0.5 unit.  Here is the STL for a clone sloped merge plate with a straight track and two 120° curves.

1-unit plate with two 120° curves, half-height slope merge plate with straight and two 120° curves 

"Skytrax"

Ravensburger seem to be struggling with marketing their most recent Gravitrax development which they are calling "Gravitrax Skytrax", located in the "Games" section (!) of their UK web site.  Skytrax plates are double-unit items which stack on each other, a combination of plate and pillar.  They have their own half-unit 5 mm "pillar" part which is needed when stacking with a standard Gravitrax plate.  Here is a clone of the Skytrax pillar/plate and of the double-unit Skytrax merge with straight and two 120° curves.

Half-unit Skytrax pillar/plate 

2-unit Skytrax merge plate with straight and two 120° curves

©2025 Lester Gilbert