Build a futuristic marble city you power by hand. This 294-piece marble run pairs laser-cut basswood with metal and high-transparency acrylic for a striking gray-black, industrial "future city" look. Crank the handle and watch steel balls climb the lift, then race down 2.5 meters of spiral slopes, twisting tracks, and switches—no electricity required, driven entirely by gears and gravity.

Inspired by Rube Goldberg's mechanical contraptions, it's a STEAM-rich build that brings gears, transmission, and energy conversion to life. Includes a tower distributor, crane and wheel lifters, slides, and 10 marbles. Glue-free mortise-and-tenon assembly, with an optional link pack to connect it to the Marble Spaceport for an even bigger run.

A rewarding ~7-hour build at 4-star difficulty—and a mesmerizing desk display once finished. A great gift for makers, engineers, and puzzle fans.

• 294 laser-cut pieces + 10 marbles; wood, metal, and acrylic
• Hand-cranked, power-free gear-and-gravity mechanism
• ~7-hour build, 4-star difficulty; ages 14+
• Assembled size: approx. 12.8 x 8.4 x 9 in
• Note: wax (for smooth running) may be omitted from some shipments; ordinary candle or beeswax works