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Twin tower marble runs
Two spiral towers side by side, joined by a bridge on aqueduct arches. The marble winds down the first tower, rolls across, and finishes its run down the second.
Start from a preset
Each preset opens in the generator, ready to tweak, test and download.
How it works
- The first spiral leaves its tower along a straight bridge that meets the second tower’s spiral exactly where it starts.
- The bridge stands on fins with pointed arches. Where the second tower’s lower levels pass underneath, the fins get tunnels.
- If both towers would be too wide for your printer, the spirals get steeper instead, so it always fits the bed.
Settings you can change
| Tower radius | A minimum: towers grow if the levels would collide. |
|---|---|
| Gap between towers | Sets the bridge length. |
| Bridge height | Where the bridge crosses, from near the bottom to near the top. |
Every style also lets you pick your printer, marble size (6 mm BBs to 25 mm shooters), groove shape, slope, wall height, base plate, label and colours.
Printing tips
Two towers make a wide print: on smaller printers use a smaller gap or a 6–8 mm ball. Slice with supports off, 0.2 mm layers and 3–4 walls. The full print guide covers slicer settings and troubleshooting.
Other styles
- Spiral marble run towers: A spiral tower winds a track down around a central core.
- Zigzag marble runs: A zigzag run (or drop wall) sends the marble along a ramp, drops it onto the next ramp going the other way, and repeats all the way down.
- Freeform marble runs: A freeform run wanders across the printer bed in loops and bends, held up by fins with pointed arches (like a Roman aqueduct) or by thin pillars (like a roller coaster).
- Zigzag tower marble runs: A zigzag tower wraps a drop wall round a square core.
- Racing marble runs: A wave racer is a zigzag wall with several identical lanes side by side.
- Vortex cascade marble runs: A vortex cascade is a chain of funnel bowls.
- Loop-the-loop marble runs: A steep drop, a vertical loop, then a U-turn back alongside to the finish.