ERRF 2023 was my first 3D printing convention and I had fun designing derby cars for the “Creatively Fast Class.” Rules at the end of this description. Note: I uploaded a single STL, but none of these are intended to be printed as a single piece. See “How I printed it” section for addition info.

Lightyear Zero Derby Concept

How I designed it: 
I made a side profile silhouette of the Lightyear Zero concept car, turned it into an SVG and used that to create the general shape of the model in Tinkercad. 

Why the Lightyear Zero: 
It is supposed to be one of the most aerodynamic production cars ever made.

How I Printed it:
Printed on a Bambu Lab X1C with AMS using Polymaker PLA, tires printed using TPU and fuzzy skin. Split the STL to objects in the slicer and print the wheels, tires, and body separately. The lightning pattern is meant to be printed as part of the body, not printed and inserted later. I suggest using modifiers to up infill of the axles and the space between them to 100% infill. Supports needed for the axles.

Cocoa XPress Derby Car

How I designed it: 
I wanted to incorporate some of the most recognizable chocolates ever created (Hershey bar, Reese's, Toblerone) so found premade models of each, uploaded to Tinkercad and combined until I was happy. I also embedded the Cocoa Press logo into the Reese's Cup spoiler and dubbed it the Cocoa XPress.

How I Printed it:
Printed on a Bambu Lab X1C with AMS using Overture Chocolate brown PLA and Polymaker Matte Rainbow for the lettering. Split the STL to objects in the slicer and print the wheels, tires, and body separately. No supports needed

E3D Buggy Derby Car

How I designed it: 
Turned the E3D Buggy Torture Test into a derby car in Tinkercad! Unfortunately, it bottomed out during the race and didn't reach the end of the track I may adjust the print at some point but for now it's definitely a fun print. 

How I Printed it:
Printed on a Bambu Lab X1C with Polymaker Galaxy Dark Blue PLA and TTYT3D Silk Red, Blue, and White for the logo on the roof. I used automatic tree supports in Orca Slicer which helped the roof from sagging. Split the STL to objects in the slicer and print the wheels, tires, and body separately.

Recreator3D Bottle Derby Car

How I designed it: 
Found a “Coke” bottle design and turned it into a derby car in Tinkercad. I wanted to play with having larger wheels in the back for added weight.

How I Printed it:
Printed on a Prusa Mini+ using pulltruded filament from Body Armor 1L bottles for the wheels, Sunkist 2L bottles for the body, and Seagrams Ginger Ale 2L bottles for the text. I used a rubber mallet to push the recreator logo into the body before the final assembly. When printing with pultruded filaments follow the basic guide from Recreator3D, but to dial in your tolerances I suggest printing flow rate cubes (https://www.printables.com/model/217097-flow-test) and adjusting your extrusion multiplier accordingly then a quick tolerance print (https://www.printables.com/model/39969-quick-tolerance-test) to test before committing to a larger print like this one. Also, I used the filament runout sensor rather than splicing all the filament runs together. Split the STL to objects in the slicer and print the wheels, tires, and body separately. Painted on supports in Prusa Slicer for the axles. 

3D Printed Derby ERRF 2023

This year ERRF will have three classes with a stronger focus on the awesome creativeness of our 3d printing makers. The Creatively fast class allows you to use your imagination to make your fully or almost fully 3d printed car fast with minimal rules with the exception that the car must work on the track without disturbing other race cars or damaging the track in any way. 

The Creatively Fast Class Rules

• General
  • All the rules for the Creatively Fast class are centered around having a fully printed car (as much as possible, if not all of the car) that is compatible with the track and can race to the finish without impeding other racers. 
  • All weight is to be 3dprinted, no paint (lets see those layers), the car must work on the track and fit within the tech dimensions, minimal rules other than that. Nothing mechanical, no added propulsion, nothing but the beauty of 3d printing, and maybe a couple pairs of axles. 
  • 3D Print all of your car with the exception of axles if need be, and a dry lubricant! That’s it!!!

Cars must comply with the following to work on the race track:

• Weight: not to exceed 6.0 ounces on a scale accurate to 1/10 ounce. For scales that have more than a single digit beyond the decimal point, the maximum weight is 6.0500000
• Width: The maximum width of the car, including wheels and axles, must not exceed 2-3/4 inches. (69.85mm)
• Length: Not to exceed 8 inches
• Height not to exceed 3 inches
• Bottom Clearance: The distance between the bottom of the wheels and the bottom of the lowest point of the car other than the wheels must be at least 3/8 inch. (9.5mm)
• Width Between Wheels: The distance between the innermost edges of the left and right wheels must be at least 1-3/4 inches. (44.5mm)
• Wheels: must be printed and not fall apart while racing.  In order to reduce risk of damaging the track surface no part of the car shall contact the track other than the wheels while racing.

****Your car must be built to go down the track, all the way, and not interfere with other cars or leave the track or anything on the track at any point, cars that violate this rule will be removed from the race. It is the racers responsibility to ensure the car rests securely against the starting pin when placed in the starting position and is wide enough to trigger electronic finish lines.****