Marble Race

SUMMARY

This is a marble race! I've made a couple of updates to the model based on feedback. Notes on the updates are at the bottom! Place at least two marbles at the starting line and let them race down the slope and through different obstacles. The track can be rearranged for a different race each time. The race is a maximum of 8 units long but there are currently 9 different track sections available for use. Print all 9 to mix and match or print duplicates of your favorites. The race set also has a starting line with a gate and a finish line to catch the marbles. It has been designed for standard 16mm marbles and will probably work best with those. If you have smaller options from the Bambu store or elsewhere they should work as well (though I have not tested this). All parts are designed to fit on the Mini print bed and multiple objects can be printed simultaneously on the standard print bed.

ASSEMBLY

There are 8 base sections as labeled in the print profile. Each base section is numbered (1 - 8). Number 1 is the lowest base supporting the very last track section of the race and 8 (or the largest number you want to print) being the very top base supporting the first track section of the race. The bases have pegs at the top of each column that fit into each of the track sections. Unfortunately, the height of the bases is what limits the number of track sections. I might be able to get one or two more bases allowing the race to be extended by a track section or two. If there's interest in this let me know. You can also build your own bases our of books, down a flight of stairs, etc. and make the race as long as you want.

The track sections are designed with mating dove tails. Once the track section is supported by the base, the dove tails fit with each other to hold the track together.

The starting line requires a little extra assembly. It prints in 4 parts: the starting track section, the rotating gate, and two turn knobs. The gate slides into the starting track section and then a knob is attached to each side of the gate. The knob has a lose fit to accommodate different printer tolerances. I'd recommend gluing the knobs in place. Once assembled, the starting gate fits onto the tracks with the same dove tail as the track sections. However, the starting gate has additional side supports that press fit over the rails of the track system. This is a much tighter fit to ensure the starting gate holds in place. It's also modular and can work with any of the track sections.

PRINTING NOTES

I've set the print profile to have 0.6mm line width on most of the objects. Don't worry! A 0.4mm nozzle prints a 0.6mm line width just fine! I printed all of my components using a 0.4mm nozzle. The 0.6mm line width reduces printing time since it only has to print 2 walls instead of 3 yet no strength is lost because the overall wall width is the same. You're welcome to reduce these back to 0.4mm line width in the print profile if you'd like. Just make sure you increase the number of walls to 3 or more if you do so.

All of the track sections can be mirrored. This can create some fun options with a few of the track sections that are single sided. If you're using my print profile, just right click on the track section you want to mirror, hover over “Mirror” and then click “Along X axis”.

The bases have added walls. Because the bases get pretty tall, I've added additional walls to help with strength.

Several of the track sections have sloping or curved geometry. I've set these track sections up with variable layer height to help with print quality. The downside is this slows the printing time down. If you are less concerned with quality you can remove this.

I've added a special base for the starting line. It is for the full height of the race (using all 8 sections). If there is desire for support when not using all 8 sections please let me know. 

There are two options for a finish line. One is just a general catch all. The other shows the order in which the marbles finish. The ordered one needs to be printed vertically as it's oriented in the print profiles. This will ensure it's proper function. I didn't need to print mine with a brim but depending on your bed adhesion a brim might be a good idea. 

One additional note about print orientation. A few of the platforms print much cleaner if they are printed vertically. I've set them up this way in the print profile and recommend they be printed this way. I've added minimalist brims which worked for me on a Bambu Lab textured PEI print bed. If you have issues with bed adhesion on these vertical prints you can increase the bed temp by 5˚, change the brim settings, or simply print with the platform flat on the bed. If you change the print orientation make sure you trun off supports for that object. 

UPDATES

May 5, 2025: I've added a funnel finish line so the marbles stack in the order they finished. It needs to print vertically as in the print profile. The slope to this part is more gradual than I'd like but to make it compatible with all the exiting prints already out there, it needs to be this way. Because the slop is so gradual,  the best print orientation is vertical. I've added a brim in the print profile for ensure completion but if you have excellent bed adhesion it shouldn't be necessary. Finally, the gradual slope also causes a “traffic jam” on occasion. My novice CAD skill and poor forethought are to blame for this (I apologize!). If there is a big desire for a better functioning funnel finish line that may require some extra printing, let me know. 

I added a base to support the starting line. Unfortunately, you'll have to print a new starting line to get the base to work with it. I had a whole bunch of issues getting the alignment pegs to match with the old starting line. Again, my novice CAD skills are to blame and I apologize. 

I added a U Turn track section. Right now, this track section is designed to take the place of track section 5 and it's support base. Because of the unique geometry and 3D printing requirements, this section prints with it's own integral base section and thus only fits in the place of track 5. So if you print the full 8 track set you'd have 3 track section above the U Turn and 4 sections Below. Let me know if there is desire to have this fit in a couple of the other track slots. Lastly, there are two versions. I found that regardless of how the marbles enter the U Turn, they always follow the outer edge. So V2 has a bump on the outer edge to redirect them. I'll keep working on more track sections over time! 

March 6, 2026: After a little more time than I would have liked (I apologize!), I've finally had the chance to add some more platforms and an updated base. I've added 5 new platforms: Zig Zag V2, Fork in the Road, Fans, The Carousel, and The Dropoff. One specific note about The Carousel. It requires one 608ZZ bearing. I tried and tried to find a way to print this without additional hardware but I couldn't get it to spin smooth enough to reliably turn when marbles hit it. Bambu Lab sells them in packs of 2 (linked below) in a standard or high performance version. I'd recommend the high performance version but the standard one works fine. You can also order some from Amazon in larger quantities.  I've also added an additional base with stacking sections. Users can now print the stacking base with as many spacers as they'd like to extend the track beyond the original 8 platforms. In the print profile the base, the top supports, and the set of 4 spacers will make a base for platform 9. Add however many sets of 4 spacers to 8 and that will tell you what platform you have. For example, 3 sets of spacers (12 spacers) = platform 11. When assembling the stacking bases make sure final top columns are paired together (short ones up front, tall ones in the back). I'd also recommend gluing the parts together for all the stacking bases. The tolerances are slightly loser to make for easier assembly but this means they are slightly more unstable. A special shout out to @Marinusss for some very specific platform suggestions. And thanks to everyone who has printed the model previously and all of the different suggestions. I do my best to read every comment but I'm sure I miss a few (my apologies again!). I'm always open to more suggestions so leave a comment or shoot me a direct message. I'll keep posting updates as time goes on.